JPH07287104A - Optical path converter and optical path converting array - Google Patents

Abstract

PURPOSE:To provide an optical path converter which can rotate a flat light by 90 deg. and the optical path converting array which arrays plural flat lights arrayed in a broken-line shape in a ladder shape facilitate the convergence thereof. CONSTITUTION:A flat light is made incident on the optical path converter 1, which has a 1st gradient index lens part 2 and a 2nd gradient index lens 3 having the same focal length formed at a distance twice as large as the focal length, so that the long axis of the light slants at 45$ to the center line of the linear gradient index lens part 2, and then the long axis and short axis of an image are inverted to obtain an image similar to that formed by rotating the flat light by 90 deg.. This optical path converter 1 is slanted at 45 deg. to the array direction and respective flat lights of lights in the broken-line shape are rotated by 90 deg. and array in the ladder shape. Consequently, a multistripe array semiconductor laser light is converged with high efficiency and made narrow.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical path converter and an optical path conversion array for converting the shape of transmitted light, and more particularly to an optical path suitable for converting a flat light shape using a semiconductor laser array as a light source. The present invention relates to a converter and an optical path conversion array.

[0002]

2. Description of the Related Art Improving the technique for converging laser light and utilizing light energy is one of the most important issues in the laser processing field. A YAG laser is often used as a laser generator used for ordinary laser processing. However, the YAG laser has low conversion efficiency of light output with respect to electric input, and requires a relatively large-scale device and a large amount of cooling water.

On the other hand, a laser device using a semiconductor laser element is known as a laser device which has a high conversion efficiency of electric input / optical output, and is compact and does not require a large-scale cooling device. A multi-striped array semiconductor laser is known as a semiconductor laser device that can obtain a relatively high output. This is because a semiconductor chip is engraved with 10 to 100 stripe-shaped active layers, and a dashed line-shaped light source for emitting a laser beam from each of 10 to 100 line-segment-shaped points arranged one-dimensionally is used. Have

By the way, it is preferable that the laser beam can be guided to one optical fiber with high efficiency in order to satisfy the demand to provide a laser light source having high usability not only in the laser processing field but also in the medical field. Therefore, when using the multi-stripe array semiconductor laser, the light emitted from each active layer is guided to each individual optical fiber to form a fiber bundle, and the light emitted from the end faces of these optical fibers is newly collected. Measures such as lighting are taken. However, in this case, the coupling loss of the optical fiber is large, and it is difficult to guide the laser light emitted in a broken line shape to a single optical fiber and narrow it down to a high density.

On the other hand, solid-state lasers using semiconductor laser light as an excitation light source have been attracting attention because they can achieve high efficiency, long life, and miniaturization. According to the edge pumping method in which the solid-state laser is optically pumped from the optical axis direction of the solid-state laser, a highly efficient single basic lateral laser is obtained by matching the pumping space of the semiconductor laser output light with the mode space of the solid-state laser oscillation. Although mode oscillation can be realized, for example, when the multi-stripe array semiconductor laser light is focused using a single lens, the total length of the light source of the multi-stripe array semiconductor laser is about 10 mm.
At the time of focusing, only a beam spot having a diameter determined by the magnification of the lens can be obtained, and it has been impossible to obtain a beam spot having a diameter of 1 mm or less that is practical as an end-pumping excitation light source.

Therefore, as shown in FIG. 9, laser beams emitted from the active layer 21 of the multi-striped array semiconductor laser device are individually collimated by using a microlens array 31, and then a beam spot is formed by using a focusing lens 26. There is a method of narrowing the BS to one place and superimposing all the stripe lights. According to this method, the beam spot diameter is obtained by multiplying the full width of each active layer 21 by the magnification determined by the focal length between the microlens 31 and the focusing lens 26, and the active layer of the multi-stripe array semiconductor laser generating element is obtained. The vertical component with respect to 21 can be narrowed down, but in order to prevent adjacent stripes of light from overlapping each other, each microlens corresponding to each stripe of light is placed close to the emission surface of the semiconductor laser generating element. Since it is necessary to arrange them, it is necessary to use each microlens with a short focal length, and the magnification determined by the combination with the focusing lens must be large, and it does not reach a practical focused spot diameter. .

[0007]

As shown in FIG. 10, a multi-stripe array semiconductor laser device 22 usually has 10 to 100 active layers 21 each having a width of about 100 μm to 200 μm in a plane having a total width of about 10 mm. It is arranged at regular intervals. Therefore, a broken line light source that emits 10 to 100 laser beams from one semiconductor laser generating element is provided. Each of these striped lights is emitted from a flat light source, and the beam emission angle has a vertical component θV relatively large with respect to the active layer and is about 40 ° to 5 °.
The parallel component θH is relatively small and is about 10 °. The width of the light emitting source is relatively narrow in the vertical component and is 0.1.
μm to 1 μm, and the parallel component is relatively wide and 100 μm to 200 μm as described above.

Since the vertical component θV can be easily narrowed down as described above, if the vertical components θV and the parallel components θH of the laser light are interchanged and the respective beams are arranged in a ladder shape, the parallel component θH can be narrowed down. Can be easily focused, and the light can be easily focused as a whole. That is, first, the active layer 2 is formed by using a micro-cylindrical lens array having a short focal length.
The component θV perpendicular to the extending direction of 1 is condensed, and then the vertical component θV and the parallel component θH are exchanged, and the parallel component θH is condensed using a cylindrical lens having a long focal length. Finally, a focusing lens is used to focus both components on the beam spot. Here, for the vertical component, since the micro-cylindrical lens is arranged close to the light source, the magnification is high, but the focused spot diameter is not so large because the width of the light source is extremely narrow. With respect to the parallel component, since the cylindrical lens is arranged away from the light source, the magnification can be suppressed to a small value, so that the focused spot diameter can be reduced.

The present invention has been made in view of the above circumstances, and a first object thereof is to separate a collimator lens from a light source when collecting a component parallel to a semiconductor laser active layer. Another object of the present invention is to provide an optical path changing device that can reduce the beam spot diameter that is narrowed by reducing the magnification determined by the combination with the focusing lens. In addition to the above, a second object of the present invention is to use as a light source for laser processing by condensing a large number of laser beams emitted from a multi-striped array semiconductor laser device with a large radiation angle and narrowing them down into a single spot. An optical path conversion array that can efficiently generate a solid-state laser fundamental wave so that it can guide light to an optical fiber or match the excitation space by the semiconductor laser output light to the mode space of solid-state laser oscillation. To provide.

[0010]

According to the present invention, such an object has the highest refractive index in the vicinity of the first axis on the incident surface orthogonal to the optical axis of the flat transmitted light. ,
A first distributed index lens portion having an internal composition that gradually changes as it is separated from the axis, and the first axis on an emission surface orthogonal to the optical axis of the transmitted light. The refractive index is the highest in the vicinity of the parallel second axis, and the internal composition is gradually changed so as to be away from the axis, and is the same as that of the first distributed index lens section. The second distributed index lens portion having a focal length is formed of an optical glass body formed to be separated from each other by a distance that is twice the focal length of each distributed index lens portion, and the flat transmitted light is The light is incident from the incident surface such that its major axis is inclined at 45 ° with respect to the first axis, and the image is inverted about the plane passing through the first and second axes to rotate the transmitted light around the optical axis. Characterized by emitting light equivalent to rotating 90 ° Optical path changer, and the refractive index is highest in the vicinity of the first axis on the incident surface orthogonal to the optical axis of the flat transmitted light, and the internal composition gradually decreases so as to be away from the axis. And the refractive index in the vicinity of the first distributed refractive index lens portion and the second axis parallel to the first axis on the exit surface orthogonal to the optical axis of the transmitted light. Is the highest, and the internal composition gradually changes so as to gradually decrease as it is separated from the axis, and the second distributed index lens part having the same focal length as the first distributed index lens part, A direction in which a plurality of optical path changers made of optical glass bodies formed apart from each other by a distance twice the focal length of each of the distributed index lens parts are inclined at 45 ° with respect to the first and second axis lines. Are arranged in a line and are formed into a plurality of flat transparent Light is made incident from the incident surface of each of the optical path changing devices so that the major axis thereof is inclined by 45 ° with respect to the first axis line, and the image is inverted around the plane passing through the first and second axis lines. It is achieved by providing an optical path conversion array characterized in that the light is arranged and emitted in a ladder shape.

[0011]

According to the optical path changing device of the present invention, the incident flat light is bent by the first distributed index lens portion in accordance with the refractive index at the incident position, and is totally inverted about the center line of the lens. Then, the light is emitted from the second distributed index lens portion in a twisted state in which the flat direction is rotated by 90 °. That is, each of the distributed index lens portions functions as a cylindrical lens, and the positional relationship between the lens portions can be easily adjusted as compared with the case where different lenses are combined. Further, if a plurality of the above optical path changers are arranged at an angle of 45 ° and linear light that is connected in series in the form of a broken line is passed through these, they are converted into light that is arranged in a ladder. As a result, the light emitted from the multi-striped array semiconductor laser device is first condensed into vertical light into linear light that is connected in series in the form of a broken line, and is further converted into light that is arranged in a ladder, and then the parallel component is collimated. With this configuration, even if the optical distance between the laser element and the collimating lens is long, adjacent stripes of light do not overlap with each other, and the multi-striped array semiconductor laser light can be superposed and narrowed down to a minute spot.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to specific embodiments shown in the accompanying drawings.

First, the principle of optical path conversion of the optical path converter of the present invention will be described. 1 is a perspective view of an optical path changer 1 to which the present invention is applied, and FIG. 2A is an optical path changer 1 shown in FIG.
2 (b) is a front view of the optical path changing device 1 of FIG. 2 (a). The optical path changer 1 has one end surface which is an entrance surface 1a.
And is made of a flat plate-shaped optical glass body having the other end surface as the emission surface 1b.

On the incident surface 1a side of the optical path changer 1, the one-dimensional distribution of the refractive index is highest at the center line (first axis) O ₁ in the thickness W direction of the incident surface 1a, and this center The first distributed index lens portion 2 is formed so as to gradually decrease as it is separated from the line O ₁ . In addition, the optical path changer 1
On the exit surface 1b side of the first distributed index lens portion 2
Similarly to the above, the one-dimensional distribution of the refractive index is highest at the center line (second axis) O ₂ in the thickness W direction of the emission surface 1b, and gradually decreases as the distance from the center line O ₂ increases. The second distributed index lens portion 3 is formed. The intermediate portion 4 between the first distributed index lens portion 2 and the second distributed index lens portion 3 has a uniform refractive index.
Note that the length (L) of the optical path changer 1 is determined by a plane in which incident light passes through the center lines O ₁ and O ₂ depending on the correlation with the refractive index distribution characteristics of the distributed index lens portions 2 and 3. The focal length of each of the distributed index lens portions 2 and 3 is set to be about twice the focal length of each of the distributed index lens portions 2 and 3 so that the images are just inverted and emitted as an image of the same size.

Here, the light rays a, b, d, and e that are incident from the right incident surface 1a in FIG. 2 (a) are inside the optical path changer 1 according to the difference in the refractive index of the portions through which they pass. Go through
Then, a ', b', d ', and e'become emitted from the emission surface 1b on the left side. In addition, the light ray c incident on the center of the optical path changer 1
It goes straight inside along the central plane and emerges as c '. That is, by arranging the first distributed index lens section 2 and the second distributed index lens section 3 having the same focal length apart from each other by twice the focal length, an inverted image of the same size can be obtained. .

On the other hand, flat light (light emitted from the semiconductor laser element) B is incident on the incident surface 1a of the optical path changing device 1 in a direction orthogonal to the incident surface, and its optical axis is the incident surface 1a.
It is set so as to pass through the center O _{0 of a} and the major axis of the flat light B is inclined by 45 ° with respect to the center lines O ₁ and O _{2 in the} thickness W direction. Then, the flat light B incident on the incident surface 1a from the incident surface 1a has a cross section represented by a line segment P1Q1.
The light is refracted by the distributed index lens unit 2 of FIG. 2 and is focused at an intermediate portion in the optical path changing device 1 (line segment P2Q2), and then inverted to reach the second distributed index lens unit 3. Then, the light is refracted by the second distributed index lens portion 3 and emitted from the emission surface 1b (line segment P
3Q3), proceed in the original direction. Here, the incident surface 1a and the optical axis of the flat light B are orthogonal to each other, and the long axis of the flat light B is the central line O ₁
Since the flat light B is inclined by 45 ° with respect to, when the flat light B is symmetrically inverted with respect to the plane passing through the center lines O ₁ and O ₂ , the flat light B is rotated by 90 ° about the optical axis. become.

In order to form each of the distributed index lens portions as described above, for example, the center line O of a plate-shaped glass body is used.
Slits are provided only in the ₁ and O ₂ parts so that Na ⁺ ions
The refractive index distribution may be formed by substituting g ⁺ ions and utilizing the ion diffusion distribution. If this is performed on the first and second distributed index lens portions 2 and 3 at the same time, two distributed index lens portions having similar optical characteristics can be easily formed, and the positional relationship between them can be improved. No separate adjustment is required.

FIG. 3 shows an optical path conversion array 5 in which a plurality of the optical path converters 1 described above are arranged to process the light emitted from the multi-stripe array semiconductor laser device. Here, the multi-stripe array semiconductor laser device 22 includes the active layer 21.
The light emitting end faces of are arranged in a broken line shape (see FIG. 10), and the vertical component θV of the light emitted from the light emitting end faces of each of the active layers 21 is condensed by using a cylindrical lens or to generate a broken flat light. It shall be incident. Each optical path changer 1
Is such that the plane of incidence 1a is orthogonal to the optical axis of each of the above-mentioned flat lights, and the long axis of the plane of flat light and the center line O _{1 of the} plane of incidence 1a are inclined by 45 °, that is, the arrangement direction and the center line O of the plane of incidence 1a. They are arranged so that ₁ and 45 incline. Thereby, each incident flat light is rotated by 90 °, that is, the vertical component θV and the horizontal component θh of the laser light are exchanged and arranged in a ladder shape to be emitted.

In this way, a large number of stripe lights B1 which are arranged in a straight line in a straight line are converted by the optical path conversion array 4 into stripe lights B2 which are apparently arranged in a ladder shape.

In the above structure, one optical path changer 1 is associated with one stripe of light. Therefore, it is necessary to prepare an extremely small optical path changer for the arrangement of a large number of active layers having a small width dimension. However, in practice, one optical path changer may correspond to a plurality of stripe lights. In this case, a large number of stripes are divided into the same width as the arrangement pitch of adjacent optical path changers, and each divided element is divided into 9 stripes.
Although it is rotated by 0 degree, even in this case, the laser light can be narrowed to the same extent as the arrangement pitch of the optical path changers.

Using the above optical path changer, for example, 200 μm
FIG. 4 shows a semiconductor laser condensing device 23 that condenses the laser light emitted from the multi-stripe array semiconductor laser device 22 in which twelve active layers 21 each having a width of 800 μm are arranged. In FIG. 4, after the vertical component for the active layer 21 is collimated by the cylindrical lens 24 arranged close to the multi-striped array semiconductor laser device 22, the optical path converter 1 (each converter is arranged corresponding to each active layer 21). The long axis and the short axis of the cross section of each stripe light are inverted by the optical path conversion array 5 in which the inclination of 45 ° with respect to the surface) is arranged at a pitch of 800 μm.

Next, a component parallel to the active layer is collimated by the cylindrical lens 25 arranged so as to collect the light emitted from the optical path conversion array 5. Finally, the focusing lens 26 is used to narrow down the laser light. Thereby, a beam spot BS in which a plurality of stripe lights are superposed at the focal position is obtained.

In this way, the focusing lens 2
Since the ratio between the distance between 6 and the beam spot BS and the distance between the multi-striped array semiconductor laser device 22 and the cylindrical lens 25 can be made small, the beam spot condensed to an extremely small diameter (diameter 400 μm). BS is obtained. As for the vertical component, although the ratio between the distance between the focusing lens 26 and the beam spot BS and the distance between the multi-stripe array semiconductor laser device 22 and the cylindrical lens 24 becomes large,
The narrowed beam spot diameter does not become large because the width of the light source is sufficiently small.

Needless to say, instead of the above-mentioned cylindrical lens, a cylindrical lens having the same function as that of the cylindrical lens may be used.

Laser light condensed by the above semiconductor laser condensing device can be guided to an optical fiber (core diameter 400 μm). As shown in FIG. 5, the laser light condensed by the focusing lens 26 is used. Is guided to the optical fiber 27, a light guiding efficiency of 60% of a semiconductor laser output of 10 W can be obtained.

Further, it is also possible to optically excite the solid-state laser by using the laser beam condensed by the semiconductor laser condensing device, and as shown in FIG. 6, the laser beam condensed by the focusing lens 26 is used for YAG. When optical pumping is attempted by end face pumping of a solid-state laser element 28 such as a laser, a 3 W YAG laser output is obtained using a 10 W semiconductor laser.

Further, as shown in FIG. 7, when the laser light focused by the focusing lens 26 is guided to the optical fiber 27 and the solid-state laser element 28 is optically excited by end face excitation, a 2 W YAG laser output is obtained. To be

[0028]

As described above, according to the present invention, the first distributed index lens part and the second distributed index lens part having the same focal length are separated from each other by a distance twice the focal length. The long axis of the flat light is the first
When the light is incident so as to be inclined at 45 ° with respect to the center line of the distributed index lens portion, the long axis and the short axis of the image are reversed, that is, the same image as if the flat light is rotated by 90 ° is obtained. At this time,
Each of the distributed index lens portions functions as a cylindrical lens, and the positional relationship between the lens portions is easily adjusted as compared with the case where different lenses are combined. If this optical path changer is tilted at 45 ° with respect to the arrangement direction and each flat light of the wavy line is rotated by 90 ° and arranged in a ladder shape,
High-power multi-stripe array semiconductor laser light can be condensed with high efficiency and can be narrowed down, so that a beam spot with high power density can be obtained. This makes it possible to realize particularly precise processing in laser processing and laser soldering. Further, when the condensed multi-striped array semiconductor laser light is guided to the optical fiber, the handleability of the laser light is improved. Further, according to the semiconductor laser pumped solid-state laser having the above structure, end face pumping, which has been difficult with the conventional array semiconductor laser, is possible, and a solid-state laser with high efficiency and high beam quality can be realized.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing a configuration of an optical path changing device to which the present invention is applied and a state of optical path changing.

2A and 2B are a side view and a front view for explaining the principle of optical path conversion of the optical path converter of FIG.

FIG. 3 is a correspondence diagram of an optical path conversion array to which the present invention is applied and a multi-stripe array semiconductor laser beam.

FIG. 4 is a schematic side view showing the configuration of a laser device to which the present invention is applied.

FIG. 5 is a schematic side view showing the configuration of a laser device to which the present invention is applied.

FIG. 6 is a schematic side view showing the configuration of a laser device to which the present invention is applied.

FIG. 7 is a schematic side view showing the configuration of a laser device to which the present invention is applied.

FIG. 8A and FIG. 8B are a plan view and a side view for explaining a condensing state of a conventional multi-stripe array semiconductor laser arranged in a broken line shape.

FIG. 9 is a schematic perspective view showing emission light patterns from a multi-stripe array semiconductor laser device and each active layer.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Optical path changer 1a Incident surface 1b Emission surface 2 First distributed index lens section 3 Second distributed index lens section 4 Intermediate section 5 Optical path conversion array 21 Active layer 22 Multi-stripe array semiconductor laser device 24 Cylindrical lens 25 Cylindrical Lens 26 Focusing lens 27 Optical fiber 28 Solid-state laser element 29 Resonator output mirror 30 Lens 31 Microlens O ₁ First axis O ₂ Second axis

Claims (2)

[Claims] 1. A refractive index is highest in the vicinity of a first axis on an incident surface orthogonal to the optical axis of flat transmitted light, and the internal composition gradually decreases so as to be away from the axis. The first distributed refractive index lens part that is changed, and the first distributed index lens part on the emission surface orthogonal to the optical axis of the transmitted light.
Has a highest refractive index in the vicinity of a second axis parallel to the axis, and the internal composition gradually changes so as to be away from the axis, and the first distributed index lens And a second distributed index lens section having the same focal length as that of the above-mentioned section has a focal length of 2 of each of the distributed index lens sections.
The flat transmitted light is made incident on the incident surface such that the major axis thereof is inclined at 45 ° with respect to the first axis, and the flat transmitted light is incident on the incident surface. An optical path changer characterized by inverting an image centering on a plane passing through the first and second axes and emitting light equivalent to rotating the transmitted light by 90 ° around the optical axis. 2. The refractive index is highest near the first axis on the incident surface orthogonal to the optical axis of the flat transmitted light, and the internal composition gradually decreases so as to be away from the axis. A first distributed refractive index lens portion which is changed,
The first portion on the emission surface orthogonal to the optical axis of the transmitted light
Has a highest refractive index in the vicinity of a second axis parallel to the axis, and the internal composition gradually changes so as to be away from the axis, and the first distributed index lens And a second distributed index lens section having the same focal length as that of the above-mentioned section has a focal length of 2 of each of the distributed index lens sections.
A plurality of optical path changers formed of optical glass bodies which are formed apart from each other by a distance of double are arranged in a direction inclined by 45 ° with respect to the first and second axis lines, and a plurality of the flattened flat surfaces are formed. The transmitted light such that its long axis is inclined by 45 ° with respect to the first axis, from the incident surface of each of the optical path changers, and an image is formed centering on the surface passing through the first and second axes. An optical path conversion array, which is inverted and arranged in a ladder shape and emitted.