JPH04338902A - Method and device for guiding semiconductor laser beam by optical fiber - Google Patents

Abstract

PURPOSE:To improve the light energy density of the semiconductor laser beam. CONSTITUTION:This laser beam 3 which is emitted by a semiconductor laser element 1 is made incident on and coupled with the incidence end surface 7 of a bundle type optical fiber 6 in the same shape with the light source 2 of the semiconductor laser element 1 through a condenser lens 4 and the projection end surfaces 8 on the projection side of the bundle optical fiber 6 are formed in the closest array. The light energy density of the semiconductor laser beam can be improved, so a body can finely be machined with the semiconductor laser beam.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for coupling and guiding a semiconductor laser beam into an optical fiber and an apparatus for microfabrication of objects using a semiconductor laser beam.

0002

2. Description of the Related Art As a method for coupling a semiconductor laser beam into an optical fiber in an apparatus for microfabrication of an object, for example, in the prior art, there is the following method.

1. Coupling to a single-core fiber In FIG. 8, a laser beam 3 from a light source 2 of a semiconductor laser device 1 is configured to enter an optical fiber 5 via a condensing lens 4 such as a rod lens. The aperture C of the optical fiber 5 has the following relationship with respect to the light source 2.

0004

[Equation 1] A × sin Θ1 = C × sin Θ2 However, A: Width of light source 2 B: Thickness of light source 2 Θ1: Emission of laser beam 3a from light source 2 to condensing lens 4 perpendicular to the cemented surface of the semiconductor laser Angle Θ2:
Laser beam 3 from condenser lens 3 to optical fiber 5
angle of incidence of b

[0005] Therefore, when a semiconductor laser device with a high output power is used, the width A of the light source 2 becomes large, and in order to achieve efficient coupling, the aperture size C of the optical fiber 4 must also be made large. Therefore, in order to increase the optical coupling rate, it is necessary to use an optical fiber 5 with a large diameter (or an optical fiber with a high numerical aperture).

2. Butt coupling Figure 9 shows this coupling method, in which the optical fiber 5 is connected without a lens and only with a small clearance L.
This is a method in which the light is directly coupled to the light source 2 (not shown) of the semiconductor laser device 1.

[0007] In this case as well, basically the above 1. The diameter of the optical fiber 5 needs to be larger than the width A of the light source 2.

Therefore, in the case of input coupling using a large-diameter optical fiber, since the diameter of the output side of the optical fiber is equally large, the coupling efficiency improves in practice, but the optical energy density of the light source on the output side does not improve. There are drawbacks.

[0009]

[Problem to be solved by the invention] Therefore, this invention
This is intended to improve the optical energy density mentioned above.

0010

[Means for Solving the Problems] Therefore, the present invention has solved the above problems by using bundled optical fibers.

[0011]

[Operation] Therefore, the laser beam emitted from the semiconductor laser element can be coupled to the optical fiber with high efficiency, and by increasing the number of optical fibers used and reducing the total cross-sectional area of the optical fiber, the light on the output side can be The energy density can be increased, and therefore, it has become possible to microfabricate objects with a semiconductor laser beam, which was not possible with conventional techniques.

0012

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory perspective view of an embodiment of a device for coupling and extracting a semiconductor laser beam into an optical fiber according to the present invention, FIG. 2 is a side view of FIG. 1, and FIG. 3 is a plan view of the light source of the semiconductor laser device of FIG. The enlarged views, FIGS. 4 to 6 are explanatory diagrams of image formation on the input end face of the optical fiber, and FIG. 7 is an explanatory diagram of the lead-out end face of the bundle-shaped optical fiber used in the present invention.

First, the overall structure of the apparatus of the present invention will be explained using FIGS. 1 and 2. 1 is a semiconductor laser element 1
It is packaged with a light source 2. The light source 2 is a rectangle with a width A and a thickness B, as ideally shown in FIG. 4 is a condensing lens, and 6 is a bundle-shaped optical fiber 6, which has an input end surface 7 and an output end surface 8. These light sources 2, condensing lenses 4 and bundled optical fibers 6 are arranged linearly with respect to the laser beam axis 14, and they are mechanically connected in a direction parallel to the laser beam axis 14 with mounting hardware (not shown). Fitted with guaranteed accuracy. The condensing lens 4 can be adjusted in a direction parallel to the laser beam axis 14 as indicated by an arrow 9, and the bundle-shaped optical fiber 6 can be adjusted in a direction 12 parallel to the laser beam axis 14, a direction 10 perpendicular to the laser beam axis 14, and a direction 10 perpendicular to the laser beam axis 14. It is configured to be adjustable in a direction 11 perpendicular to the direction 11 and a direction 13 of rotation. These adjustments are made so that all the laser beams 3a are incident on the condenser lens 4, and the laser beam 3b that has passed through the condenser lens 4 is imaged on the incident end face 7 of the bundle-shaped optical fiber 6.

The light source 2 of the semiconductor laser device 1 is as shown in FIG. 3 described above, and has a width A of about 200 μm and a thickness B of about 1 μm, for example. Before explaining the principle of the present invention, let us consider the conventional image formation for a single optical fiber 5 using FIG. 4. When a 1:1 image is formed on the condenser lens 4 (magnification is 1), the light source 2 forms an image on the incident end face of the optical fiber 5 in the shape shown in FIG. 4, and the shape of the image 15 is also A×B. The dimensions will be . If the numerical aperture of the optical fiber is a value that satisfies the incident angle Θ2 of the laser beam, the image 15 of the condensing section enters the core 16 of the optical fiber 5, resulting in the best coupling ratio in principle. The imaging magnification may be arbitrary as long as the incident conditions of the optical fiber 5 are satisfied. 17 is a cladding.

Next, the formation of images onto a plurality of optical fibers according to the present invention will be considered. As shown in FIG. 5, when the image 15 of the condenser is focused across the two optical fibers 6a and 6b that constitute the bundle-type optical fiber 6, the image 15 is focused on the two cores 18 and the two claddings. The optical energy focused on the contact portion 20 of the optical fiber 19 causes a coupling loss, but the cross-sectional area of the optical fibers 6a and 6b is equal to that of the optical fiber with a diameter half that of the optical fiber 5 in FIG. This is about half of what it would be if it were used. Furthermore, as shown in FIG. 6, if five optical fibers 6a, 6b, etc., each having a diameter one-fifth of the optical fiber 5 when one is used, the total cross-sectional area becomes one-fifth, and the cladding 19 is Contact part 20
Even taking into account the loss due to the incidence of the image 15 on the light source, a light energy density of approximately four times is obtained. Similarly, by arranging a plurality of small-diameter optical fibers in a linear manner and focusing the light, optical fiber coupling with high optical energy density becomes possible.

Next, the shape of the lead-out end face 8 of the bundle-type optical fiber 6 subjected to such input coupling will be explained. The plurality of small diameter optical fibers 6a, 6b... can be formed into an arbitrary shape of the leading end face 8 on the output side, but for the purpose of increasing the optical energy density, as shown in FIG. 7, a close-packed arrangement is used. It is best to form For example, Figure 4
If seven optical fibers 6a, 6b, etc., each having one-seventh of the outer diameter D of the cladding 17 of When the optical fibers 6a, 6b, . In this case, the dimension C is three-sevenths of the dimension D, and the area of each lead-out end surface 8 is Φ
The ratio of D and ΦC is 5.4:1.

Next, let us consider the transmitted power ratio. Compared to the laser beam that passes through the lead-out end face 8 of the optical fiber 5, the laser beam that passes through the small diameter optical fibers 6a, 6b, etc. is reduced by the amount that irradiates the cladding 19, but the core and cladding ratio of commercially available optical fibers is , is about 10:1 for large ones, and therefore, if a small-diameter bundle-type optical fiber is used, it is expected that the power loss will increase by only about 10% compared to a single-core optical fiber.

[0018]

As described above, according to the present invention, a laser beam emitted from a semiconductor laser element can be coupled to an optical fiber, and the optical energy density of the laser beam after coupling is equal to the number of optical fibers used. This can be achieved by increasing Furthermore, since the structure can be easily constructed using commercially available optical fibers, the cost is low. Moreover, it can be applied regardless of the length of the light source of the semiconductor laser element.
Power loss can also be reduced by 10% compared to conventional models. Furthermore, the present invention has many effects, such as enabling microfabrication using a semiconductor laser, which was previously considered impossible.

[Brief explanation of drawings]

FIG. 1 is an explanatory perspective view of an embodiment of a device for coupling in and out of an optical fiber a semiconductor laser beam according to the present invention;

FIG. 2 is a side view of FIG. 1;

FIG. 3 is an enlarged plan view of a light source of a semiconductor laser device used in the present invention.

FIG. 4 is an explanatory diagram of image formation on the incident end face of one optical fiber for explaining the present invention.

FIG. 5 is an explanatory diagram of image formation on the incident end faces of two optical fibers for explaining the present invention.

FIG. 6 is an explanatory diagram of image formation on the incident end faces of five optical fibers for explaining the present invention.

FIG. 7 is an explanatory diagram of a leading end face of a bundle-type optical fiber used in the present invention.

FIG. 8 is an explanatory diagram of a first example of a conventional method for coupling a semiconductor laser beam into an optical fiber and leading it out.

FIG. 9 is an explanatory diagram of a second example of a conventional method for coupling and deriving a semiconductor laser beam into an optical fiber.

[Explanation of symbols]

1 Semiconductor laser element 2 Light source 3a, 3b Laser beam 4 Condensing lens 5 Optical fiber 6 Bundled optical fiber 7 Incidence end face 8 Lead-out end face 14 Laser beam axis 15 Imaging 16, 18 core 17, 19 Clad 20 Contact part of cladding 19 A Light source width B Thickness of light source C Optical fiber diameter L Clearance

Claims (5)

[Claims] Claim 1: A laser beam from a light source of a semiconductor laser element is received by a bundle-shaped optical fiber having the same shape as the light source of the semiconductor laser element, and the laser beam is guided to the output side of the bundle-shaped optical fiber with high optical energy density. A method for introducing and extracting a semiconductor laser beam using an optical fiber, characterized by the following. 2. At least a light source of a semiconductor laser element;
A condensing lens and a bundle-shaped optical fiber are arranged on a laser beam axis from a light source of the semiconductor laser device, and the positions of the condensing lens and the bundle-shaped optical fiber are adjusted relative to the light source of the semiconductor laser device. 1. A device for introducing and extracting a semiconductor laser beam using an optical fiber, characterized in that the device is configured to allow the semiconductor laser beam to be introduced and extracted using an optical fiber. 3. The semiconductor laser beam according to claim 2, wherein the bundle-shaped optical fiber is such that individual optical fibers into which a laser beam from a light source of a semiconductor laser element enters are linearly arranged without gaps. Introducing/extracting device using optical fiber. 4. The device for introducing and extracting a semiconductor laser beam using an optical fiber according to claim 2, wherein the output side of the bundle-shaped optical fiber is formed in a close-packed arrangement. 5. The device for introducing and extracting a semiconductor laser beam using an optical fiber according to claim 2, wherein an optical fiber having a core-to-cladding ratio of each of the individual optical fibers of the bundle-shaped optical fiber is used as large as possible.