JPH10261825A - Semiconductor laser light shaping optical system and semiconductor laser-excited solid-state laser device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-output semiconductor laser-excited solid-state laser device. SOLUTION: Excitation light emitted from a semiconductor laser 11 is first shaped by means of an excitation light shaping optical system 12 for first axis and then shaped by means of an excitation light shaping optical system 13 for slow axis. The semiconductor laser 11 which emits the excitation light from the output-side end face of a solid-state laser crystal 11 and optical systems 12 and 13 are set so that the slow axis of the optical systems may become nearly perpendicular to the plane decided by the optical axes of a resonator and the excitation light. At the same time, the angle between the optical axis of the resonator and that of the optical systems 12 and 13 is made minimum within such an extent that the resonator does not interfere with the optical path of an excitation system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser beam shaping optical system and a semiconductor laser-excited solid-state laser device, and more particularly, to a simple shaping optical system for efficiently converting excitation light into laser light. The present invention relates to an output semiconductor laser pumped solid-state laser.

[0002]

2. Description of the Related Art A conventional semiconductor laser pumped solid-state laser device is disclosed in, for example, Japanese Patent Application Laid-Open No. 4-137775, and its schematic configuration is shown in FIG. This device includes a semiconductor laser 11, an excitation light shaping optical system 14, a solid-state laser crystal 21, and an output mirror 22. In this device, a solid-state laser crystal is irradiated with a semiconductor laser beam output from a light emitting region of several μm × several 100 μm at a divergence angle of about 40 ° × about 10 ° through a beam shaping optical system including a prism, and is excited. I have.

Japanese Patent Application Laid-Open No. 4-255280 discloses an array-type semiconductor laser as a pumping light source for obtaining high-power laser light. The shaping optical system for guiding the excitation light of the semiconductor laser-excited solid-state laser device to the solid-state laser crystal has a gradient index lens arrayed corresponding to each stripe of the array semiconductor laser, and condenses and collimates the output of the array semiconductor laser. It is composed of a lens array, an anamorphic prism for beam shaping the collimated square stripe light, and a focusing lens that collectively collects each stripe light and superimposes it at one location.

[0004]

By the way, Japanese Patent Application Laid-Open No.
In the semiconductor laser-excited solid-state laser device described in JP-A-137775, an emission region of the semiconductor laser is imaged on a solid-state laser crystal by a beam shaping optical system. Here, in order to convert the excitation light into laser light efficiently in the solid-state laser crystal, it is better that the excitation light profile in the solid-state laser crystal matches the resonator mode profile. For these reasons, in the conventional apparatus, the non-uniformity of the divergence angle of the excitation light from the semiconductor laser is corrected using a prism, and a laser in a light emitting region with a small aspect ratio is used. However,
Since the maximum output of a semiconductor laser having a small aspect ratio is about several W, it is very difficult to realize a semiconductor laser pumped solid-state laser device having a high output of several tens of W level.

Further, in a semiconductor laser pumped solid-state laser device using an arrayed semiconductor laser as a pumping light source, a distributed refractive index lens, a lens array, a prism, and a focusing lens are used, so that the optical system is complicated and the number of parts is increased. Was.

An object of the present invention is to provide a high-output semiconductor laser-excited solid-state laser device which is simple in shaping optical system and has high efficiency for converting excitation light into laser light.

[0007]

A semiconductor laser beam shaping optical system according to the present invention comprises an arrayed semiconductor laser and a shaping optic for separately shaping and condensing an arrayed semiconductor laser in a first axis direction and a slow axis direction of a light emitting region of the semiconductor laser. And a system. The shaping optical system consists of a first-axis shaping optical system and a slow-axis shaping optical system, and the ratio of the distance from the semiconductor laser to the first-axis shaping optical system and the distance from the first-axis shaping optical system to the light-collecting surface is calculated as follows: [Length of light-emitting area in first axis direction]: [diameter of imaging light on light-collecting surface in first axis direction], and distance from semiconductor laser to shaping optical system for slow axis and light condensing from shaping optical system for slow axis The ratio of the distance to the surface is defined as [length of light emitting area in slow axis direction]: [diameter of imaging light on light-collecting surface in slow axis direction].

The semiconductor laser-pumped solid-state laser device of the present invention separately forms a semiconductor laser for generating pumping light and the pumping light in the first axis direction and the slow axis direction of the light emitting region of the semiconductor laser to form a solid-state laser crystal. It is characterized by having an excitation light shaping optical system for guiding, a solid laser crystal excited by the excitation light, and a solid laser resonator sandwiching the solid laser crystal.

The slow axis of the excitation light shaping optical system is perpendicular to a plane determined by the optical axis of the solid-state laser resonator and the optical axis of the excitation light. Further, the solid-state laser resonator is characterized by comprising an output mirror and a reflection film provided on the solid-state laser crystal. Further, the semiconductor laser pumped solid state laser device is an active mirror type semiconductor laser pumped solid state laser device.

The excitation light shaping optical system comprises a first axis shaping optical system and a slow axis shaping optical system. The distance from the semiconductor laser to the first axis shaping optical system and the distance from the first axis shaping optical system to the solid-state laser crystal. The ratio of the distance of [1] is [the length of the light emitting region in the fast axis direction]: [the diameter of the imaging light on the solid-state laser crystal in the fast axis direction]. The ratio of the distance from the shaping optics to the solid-state laser crystal,
[Length of light emitting region in slow axis direction]: [diameter of imaging light on solid-state laser crystal in slow axis direction].
Further, the pumping light is incident on the resonator direction or obliquely with respect to the resonator direction. Further, a plurality of pumping means including a semiconductor laser and a pumping light shaping optical system are provided, and the solid-state laser crystal is excited by the plurality of pumping means.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIG. 1 shows a semiconductor laser beam shaping optical system according to the present invention. 11 is a semiconductor laser for excitation, 12 and 13 are optical systems for shaping excitation light, and 21 is a solid-state laser crystal. FIG. 1 shows a semiconductor laser, an excitation light shaping optical system,
FIG. 3 is a view of the solid-state laser crystal viewed from different directions, where the first axis direction is the short axis (several μ
m), and the slow axis direction is an axis parallel to the long axis (about 1 cm) of the light emitting region. As shown in FIG. 1, the emitted light of the semiconductor laser appears to diverge at a wide angle from the fast axis direction and at a narrow angle from the slow axis direction.

In the present invention, in order to increase the output of the solid-state laser device, an array of semiconductor lasers (bar-type semiconductor lasers) having an output of 20 W or more and a light emitting area of several μm × about 1 cm is used as the pumping semiconductor laser. I have. At this time, the divergence angle of the excitation light from the semiconductor laser is about 10 degrees in the full width at half maximum in the slow axis direction and about 40 degrees in the full width at half maximum in the fast axis direction. For this reason, in the present invention, the excitation light shaping optical system is separately provided for each of the long axis (hereinafter, slow axis) parallel to about 1 cm of the light emitting region and the short axis (hereinafter, fast axis) parallel to several μm of the light emitting region. Make up.

The excitation light emitted from the semiconductor laser 11 is first shaped in the first axis direction by a first axis excitation light shaping optical system 12 before the beam diameter is expanded. At this time, the light in the slow axis direction is the excitation light shaping optical system 1 for the first axis.
The process proceeds to the slow-axis excitation light shaping optical system 13 without being shaped into 2. The excitation light shaping optical system for the first axis is [distance from the semiconductor laser to the first axis shaping optical system] and [the distance from the first axis shaping optical system to the solid-state laser crystal].
By setting the ratio of [Emission area length in the fast axis direction] to [Diameter of imaging light on the solid-state laser crystal in the fast axis direction], that is, [several μm] to [about 1 mm], the first axis direction The excitation light from the light emitting region having a length of several μm is focused on a solid-state laser crystal with a diameter of about 1 mm.

Next, the excitation light from the semiconductor laser passes through the shaping optical system in the first axis direction, and then the slow axis direction is shaped by the slow axis excitation light shaping optical system 13 arranged near the solid-state laser crystal. 21. The divergence angle of the excitation light of the semiconductor laser in the slow axis direction is 1
Although it is not as large as about 0 degrees, but the emission length is as long as about 1 cm, the excitation light shaping optical system for the slow axis is [distance from the semiconductor laser to the shaping optical system for the slow axis] and [the solid-state light from the slow axis shaping optical system]. The ratio of [distance to laser crystal] is defined as the relationship of [length of light emitting region in slow axis direction] to [diameter of imaging light on solid laser crystal in slow axis direction], that is, [about 1 cm] to [about 1 mm]. By this, 1mm
It is possible to focus and converge an image with a diameter of the order.

With the above configuration, the excitation light from the bar-type semiconductor laser having the output power of 20 W can be efficiently focused on the solid-state laser crystal. In addition, by exciting a solid-state laser crystal by using a plurality of semiconductor lasers having a level of 20 W, a semiconductor laser pumped solid-state laser having a high output of several tens of W can be realized.

(Second Embodiment) When pumping light is incident on the surface of a solid-state laser crystal in an oblique direction, the pumping light profile deviates from the resonance mode profile when the opening angle increases, so that the pumping light is efficiently used. No longer converted to laser light. Therefore, it is important to reduce the opening angle between the optical axis of the resonator and the optical axis of the excitation light shaping optical system for increasing the output of the semiconductor laser-excited solid-state laser device.

The present invention uses an array of semiconductor lasers (bar-type semiconductor lasers) having an output power of 20 W or more and a light emitting area of several μm × about 1 cm as a semiconductor laser for excitation. The shape becomes larger.
In addition, since the slow axis direction of the excitation light shaping optical system is disposed near the solid-state laser crystal, the arrangement angle of the excitation light shaping optical system increases the opening angle, making it impossible to perform efficient laser conversion of the excitation light.

Accordingly, in the present invention, the pump light shaping optical system is arranged such that the slow axis is substantially perpendicular to a plane determined by the resonator optical axis and the excitation light shaping optical system. The opening angle between the resonator optical axis and the excitation light shaping optical system optical axis is reduced without overlapping the slow-axis shaping optical system near the solid-state laser crystal and the resonator optical axis.

As a result, the mode matching of the profile of the excitation light and the oscillation light in the crystal increases, and efficient laser oscillation can be realized. In addition, since the opening angle of the shaping optical system in the direction of the slow axis is small, a plurality of bar-type semiconductor lasers and the shaping optical system can be arranged in this direction, and the excitation intensity to the solid-state laser crystal can be increased. Become. The slow axis of the excitation light shaping optical system is parallel to the electric field polarization direction of the semiconductor laser.

[0020]

Next, an embodiment of the present invention will be described with reference to the drawings.

(First Embodiment) FIGS. 2, 3, 6, and 7
1 is a first example, and is a schematic view of a semiconductor laser-excited solid-state laser device using the excitation light shaping optical system of the first embodiment. The semiconductor laser pumped solid-state laser device includes a semiconductor laser 11, a first-axis excitation light shaping optical system 12, a slow-axis excitation light shaping optical system 13, a solid-state laser crystal 21, and an output mirror 22. The semiconductor laser 11 has a light emitting region corresponding to high output of several μm × about 1 cm.
And a semiconductor laser (bar-type semiconductor laser) having an output of 20 W or more is used. The solid-state laser crystal 21 is provided with a total reflection coat for reflecting the excited light, and forms a resonator with the output mirror 22.

The excitation light from the semiconductor laser 11 is applied to the excitation light shaping optical system 1 arranged for each semiconductor laser.
It is shaped by 2 and 13. The shaping of the excitation light is the same as in FIG. Each of the shaped excitation lights is applied to the solid-state laser crystal 21 from an oblique direction to the cavity direction.
FIG. 3 is the same as the example of FIG. 2 except that the incident direction of the excitation light to the solid-state laser crystal 21 is different. In FIG. 3, the excitation light is incident from the resonator direction.

FIGS. 6 and 7 show a resonator composed of an output mirror 22 and a total reflection coat of the solid-state laser crystal 21 which is the same as that shown in FIGS. It is shown about various forms. FIG. 6 shows an example in which excitation light is incident on the solid-state laser crystal from the cavity direction and the oblique direction. Of the pumping lights from three directions in FIG. 6, any combination of pumping lights or only two pumping lights may be used. FIG. 7 shows an example in which the excitation light is incident on the solid-state laser crystal from the cavity direction and the oblique direction, but any combination of the four excitation lights may be used, and a combination of only two or three excitation lights may be used.

(Second Embodiment) FIGS. 4, 5 and 8 show a second embodiment, in which a semiconductor laser pumped solid-state using the pumping light shaping optical system of the first embodiment is used. It is a schematic diagram of a laser device. Semiconductor laser pumped solid-state laser devices
The configuration of the resonator is different from that described above, and the solid-state laser crystal 21 is arranged between the resonators of the output mirror 22 and the total reflection mirror 23. The excitation light from each semiconductor laser 11 is
The light is shaped by excitation light shaping optical systems 12 and 13 arranged for each semiconductor laser. Then, each of the shaped excitation lights is applied to the solid-state laser crystal 21 from an oblique direction with respect to the resonator. The direction of incidence of the excitation light may be from any of the four directions in FIG. 8, and only two or three excitation lights may be used.

(Third Embodiment) FIGS. 9, 12, 13,
FIG. 14 is a view showing a third example, and is a schematic view of a semiconductor laser-excited solid-state laser device using the arrangement of the excitation light shaping optical system of the second embodiment. The semiconductor laser pumped solid-state laser device includes a semiconductor laser 11, a first-axis excitation light shaping optical system 12, a slow-axis excitation light shaping optical system 13,
It comprises a solid-state laser crystal 21 and an output mirror 22. The semiconductor laser 11 uses a semiconductor laser (bar-type semiconductor laser) having an output area of 20 W or more in the form of an array having a light emitting region corresponding to high output of several μm × about 1 cm.
The solid-state laser crystal 21 is provided with a total reflection coat for reflecting the excited light, and forms a resonator with the output mirror 22.

The excitation light from the semiconductor laser 11 is supplied to the excitation light shaping optical system 1 arranged for each semiconductor laser.
It is shaped by 2 and 13. The shaping of the excitation light is the same as in FIG. Each of the shaped excitation lights is applied to the solid-state laser crystal 21 from an oblique direction to the cavity direction.

Here, the semiconductor laser 11 is arranged such that the slow axis of the semiconductor laser 11 is substantially perpendicular to a plane including the resonator optical axis and the excitation optical axis (in this case, the same as the paper). I have. By arranging the semiconductor laser 11 so that the slow axis is perpendicular to both the optical axis of the resonator and the optical axis of the excitation light, the opening angle between the optical axis of the resonator and the optical axis of the excitation light shaping optical system can be minimized. By reducing the opening angle, the coupling efficiency between the excitation light and the laser light can be increased.

FIGS. 12, 13 and 14 show the output mirror 22.
The resonator composed of the solid-state laser crystal 21 and the total reflection coat is the same as that shown in FIG. 9 and shows various modes of how the excitation light is incident on the solid-state laser crystal 21. FIG.
2. FIG. 13 shows an example in which excitation light is incident on the solid-state laser crystal from the cavity direction and the oblique direction.

It should be noted that any of the excitation lights from the three directions shown in FIGS. 12 and 13 may be combined, or only two excitation lights may be used. Similarly, any combination of the four pumping lights in FIG. 15 may be used, and a combination of two or three pumping lights may be used.

(Fourth Embodiment) Next, FIGS. 10, 11, and 15 show a fourth embodiment. The semiconductor laser pumped solid-state laser device has a resonator configuration different from that described above, and a solid-state laser crystal 21 is disposed between the output mirror 22 and the total reflection mirror 23 resonator. Excitation light from each semiconductor laser 11 is shaped by excitation light shaping optical systems 12 and 13 arranged for each semiconductor laser. Each of the shaped excitation lights is applied to the solid-state laser crystal 21 from an oblique direction with respect to the resonator.

Semiconductor laser 1 shown in FIGS. 10, 11 and 15
The arrangement of 1 is similar to the above-described example, and the slow axis of the excitation light shaping optical system is placed on a plane (same as the paper surface) in which the slow axis of the semiconductor laser 11 is determined by the resonator optical axis and the excitation light optical axis. Are almost vertically related. Therefore, the opening angle between the resonator optical axis and the excitation light shaping optical system optical axis when the optical path of the resonator and the excitation system do not interfere can be minimized, and the coupling efficiency between the excitation light and the laser light can be increased. FIG.
Any combination of the four excitation lights can be used.
Alternatively, a combination of three excitation lights may be used.

(Fifth Embodiment) FIGS. 16 to 20 are views showing a fifth embodiment, and are schematic diagrams in which the second embodiment is applied to an active mirror type semiconductor laser pumped solid-state laser. FIG. 16 shows a basic configuration of an active mirror type semiconductor laser pumped solid-state laser. The excitation light from the semiconductor laser 11 is applied to the solid-state laser crystal 21 via the first-axis excitation light shaping optical system 12 and the slow-axis excitation light shaping optical system 13. The surface of the solid-state laser crystal 21 facing the incident surface is provided with a total reflection coat for reflecting the laser wavelength, and the output mirror 22 and the total reflection mirror 23 form a resonator and perform laser oscillation.

In the example of FIG. 16, the semiconductor laser 11 is disposed so that its slow axis direction is substantially perpendicular to a plane (in this case, the same as the paper) determined by the resonator optical axis and the excitation light optical axis. ing. Therefore, since the arrangement of the LD array constituting the semiconductor laser 11 is in the direction perpendicular to the plane of the paper, it is possible to eliminate the interference of the excitation light shaping optical system with the optical path of the resonator. The opening angle with the axis can be minimized, and the coupling efficiency between the excitation light and the laser light can be increased.

FIGS. 17, 18, 19 and 20 show examples in which the excitation light is also incident from the side of the total reflection surface of the solid-state laser crystal 21, which is different from FIGS. 17 and 18 and FIGS. Indicates whether the semiconductor laser 11 is incident from the slow axis direction or from the fast axis direction. FIG.
Either one of the two excitation lights, which are excited from the total reflection coat surface (right side in the drawing) with respect to the laser light of the solid state laser crystals 9 and 20, may be used.

[0035]

As described above, according to the present invention, the light of the arrayed semiconductor laser can be condensed on the light condensing surface with a simple lens configuration. Further, it becomes possible to use a high-output bar-type semiconductor laser for excitation, and it is possible to provide a semiconductor laser-excited solid-state laser device having a high output of several tens of watts.
Further, since the opening angle between the optical axis of the resonator and the optical axis of the excitation light shaping optical system can be reduced, it is possible to provide a semiconductor laser-excited solid-state laser device that efficiently converts excitation light into laser light.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an excitation light shaping optical system according to the present invention.

FIG. 2 is a schematic view of a semiconductor laser-excited solid-state laser device according to a first embodiment.

FIG. 3 is a schematic view of a semiconductor laser pumped solid-state laser device according to a first embodiment.

FIG. 4 is a schematic view of a semiconductor laser pumped solid-state laser device according to a second embodiment.

FIG. 5 is a schematic view of a semiconductor laser pumped solid-state laser device according to a second embodiment.

FIG. 6 is a schematic view of a semiconductor laser pumped solid-state laser device according to a first embodiment.

FIG. 7 is a schematic view of a semiconductor laser pumped solid-state laser device according to a first embodiment.

FIG. 8 is a schematic view of a semiconductor laser pumped solid-state laser device according to a second embodiment.

FIG. 9 is a schematic view of a semiconductor laser pumped solid-state laser device according to a third embodiment.

FIG. 10 is a schematic view of a semiconductor laser pumped solid-state laser device according to a fourth embodiment.

FIG. 11 is a schematic view of a semiconductor laser pumped solid-state laser device according to a fourth embodiment.

FIG. 12 is a schematic view of a semiconductor laser pumped solid-state laser device according to a third embodiment.

FIG. 13 is a schematic view of a semiconductor laser pumped solid-state laser device according to a third embodiment.

FIG. 14 is a schematic view of a semiconductor laser pumped solid-state laser device according to a third embodiment.

FIG. 15 is a schematic view of a semiconductor laser pumped solid-state laser device according to a fourth embodiment.

FIG. 16 is a schematic view of a semiconductor laser pumped solid-state laser device according to a fifth embodiment.

FIG. 17 is a schematic view of a semiconductor laser-excited solid-state laser device according to a fifth embodiment.

FIG. 18 is a schematic view of a semiconductor laser pumped solid-state laser device according to a fifth embodiment.

FIG. 19 is a schematic view of a semiconductor laser pumped solid-state laser device according to a fifth embodiment.

FIG. 20 is a schematic view of a semiconductor laser pumped solid-state laser device according to a fifth embodiment.

FIG. 21 is a schematic view of a conventional semiconductor laser pumped solid-state laser device.

[Explanation of symbols]

 Reference Signs List 11 semiconductor laser 12 first-axis excitation light shaping optical system 13 slow-axis excitation light shaping optical system 14 conventional technology excitation light shaping optical system 21 solid-state laser crystal 22 output mirror 23 total reflection mirror

Claims (10)

[Claims] 1. A semiconductor laser beam shaping optical system comprising: an array-shaped semiconductor laser; and a shaping optical system for separately shaping and condensing light in a first axis direction and a slow axis direction of a light emitting region of the semiconductor laser. . 2. The shaping optical system comprises a first-axis shaping optical system and a slow-axis shaping optical system, wherein a distance from the semiconductor laser to the first-axis shaping optical system and a focusing surface from the first-axis shaping optical system. The ratio of the distance from the semiconductor laser to the slow axis shaping optical system is defined as [the length of the light emitting region in the fast axis direction]: [the diameter of the imaging light on the light-converging surface in the fast axis direction]. The ratio of the distance from the shaping optical system for the axis to the light-collecting surface is defined as [light-emitting area length in the slow-axis direction]: [diameter of imaging light on the light-collecting surface in the slow-axis direction]. 2. The semiconductor laser beam shaping optical system according to 1. 3. An arrayed semiconductor laser for generating excitation light, and an excitation light shaping optical system for separately shaping the excitation light in the first axis direction and the slow axis direction of a light emitting region of the semiconductor laser and guiding the same to a solid-state laser crystal. A solid-state laser crystal pumped by the pumping light; and a solid-state laser resonator sandwiching the solid-state laser crystal. 4. The solid-state laser pumped solid-state laser according to claim 3, wherein the slow axis of the pumping light shaping optical system is perpendicular to a plane defined by the solid-state laser resonator optical axis and the pumping light optical axis. apparatus. 5. The solid-state laser pumped solid-state laser device according to claim 3, wherein said solid-state laser resonator comprises an output mirror and a reflection film provided on said solid-state laser crystal. 6. The semiconductor laser-pumped solid-state laser device according to claim 3, wherein said semiconductor laser-pumped solid-state laser device is an active mirror type semiconductor laser-pumped solid-state laser device. 7. The excitation light shaping optical system comprises a first axis shaping optical system and a slow axis shaping optical system, wherein the distance from the semiconductor laser to the first axis shaping optical system and the solid state from the first axis shaping optical system. The ratio of the distance to the laser crystal is defined as [the length of the light emitting region in the fast axis direction]: [the diameter of the imaging light on the solid laser crystal in the first axis direction], and the distance from the semiconductor laser to the shaping optical system for the slow axis. And the ratio of the distance from the shaping optical system for the slow axis to the solid-state laser crystal is [length of the light-emitting region in the slow-axis direction]: [diameter of imaging light on the solid-state laser crystal in the slow-axis direction]. The solid-state laser device according to claim 3, 4, 5, or 6. 8. The semiconductor laser pumped solid-state laser device according to claim 3, wherein said pumping light is incident from a cavity direction. 9. The semiconductor laser-excited solid-state laser device according to claim 2, wherein said pumping light is incident obliquely with respect to a cavity direction. 10. The solid-state laser crystal according to claim 8, further comprising a plurality of pumping means comprising said semiconductor laser and a pumping light shaping optical system.
Or a semiconductor laser pumped solid-state laser device according to item 9.