JPH0563263A - Semiconductor laser-pumped solid-state laser device - Google Patents

Abstract

PURPOSE:To ensure high power laser beam with a simplified construction keeping a higher excitation efficiency by reflecting repetitively a plurality of times pumping laser beam while transmitting said pumping laser beam through a solid state laser medium between opposing reflection surfaces of a reflection member. CONSTITUTION:A pumping semiconductor laser apparatus 2 is of a 800-820nm oscillation wavelength GaAs semiconductor laser device for example, and in the case where its temperature is kept at 25 deg.C the oscillation wavelength is of 809nm, coinciding with an absorption peak of a solid state laser medium 2. Herein, pumping laser beam L0 collimated through a collimator lens 6 is incident on the reflecting mirror 3a at an angle of theta and is transmitted through a solid state laser medium 1 while being repetitively reflected between the reflecting mirrors 3b and 3a, and further is absorbed by the medium 1 for pumping of the same. Hereby, there is ensured the incidence of a greater amount of the pumping laser beam.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser pumped solid-state laser device that uses laser light emitted from a semiconductor laser device as pumping light.

[0002]

2. Description of the Related Art In a semiconductor laser pumped solid-state laser device that uses laser light emitted from a pumping semiconductor laser device as pumping light, the pumping laser light is incident from the end faces of the solid-state laser medium, which are the entrance and exit faces of the resonance light. There are a so-called end-face excitation method and a so-called side-face excitation method in which excitation laser light is incident from the side surface of the solid-state laser medium.

In the end-face excitation method, the excitation laser light that has entered the solid-state laser medium travels a long distance in the solid-state laser medium in a direction that spatially coincides with the oscillating laser light, so that almost all of the incident excitation light is absorbed. It Therefore, there is an advantage that the excitation efficiency is high.

On the other hand, in the lateral pumping method, since the pumping laser medium is made incident from the side surface of the solid laser medium, the incident area of the pumping light can be widened. Therefore, a strong laser beam can be obtained by using a large number of semiconductor laser devices (see, for example, Japanese Patent Laid-Open No. 2-54588).

[0005]

However, of the above-mentioned conventional methods, the end face pumping method has a limitation on the amount of light that can be input because the pumping laser light must be made to enter from the end face having a small area, and high output is achieved. However, it is difficult to obtain the laser device.

In the lateral pumping method, in order to allow the pumping laser light to enter from the side surface, an entrance window for the pumping laser light is provided except for a part of a reflecting mirror provided so as to surround the solid-state laser medium. This is essential, and for this reason, the utilization efficiency of the excitation laser light emitted from the semiconductor laser device is poor, and there is a limit to improvement of the excitation efficiency.

As described above, the conventional semiconductor laser pumped solid-state laser device cannot obtain a high output when trying to improve the pumping efficiency, and conversely the pumping efficiency deteriorates when trying to obtain a high output. There was a problem.

The present invention has been made under the background described above, and a semiconductor laser pumped solid-state laser device capable of obtaining high-power laser light while maintaining high pumping efficiency with a relatively simple structure. The purpose is to provide.

[0009]

In order to solve the above problems, the present invention provides (1) a solid-state laser in which a laser beam for pumping emitted from a semiconductor laser device for pumping is arranged in a laser resonator. In a semiconductor laser pumped solid-state laser device, which irradiates a medium and excites the solid-state laser medium to obtain output laser light, in the periphery of the solid-state laser medium,
The solid-state laser medium is opposed to the solid-state laser medium, and a reflecting member having reflecting surfaces forming a predetermined angle with each other is provided, and at least a part of the exciting laser light emitted from the exciting semiconductor laser device is reflected by the reflecting member. While being incident on the surface, the excitation laser light is reflected multiple times while passing through the solid-state laser medium between the reflecting surfaces facing each other of the reflecting member, and is reflected and reflected.
In addition, as a mode of configuration 1, (2) in the semiconductor laser pumped solid-state laser device of configuration 1, a part of the pumping laser light emitted from the pumping semiconductor laser device is input to the resonant laser light of the solid-state laser medium. The structure is characterized in that the light is incident from an end face that is an emission surface, and further, as a mode of the structure 1 or 2, (3) In the semiconductor laser pumped solid-state laser device of structure 1 or 2, the pumping semiconductor laser device As a configuration characterized by using a semiconductor laser array, and as an aspect of any one of configurations 1 to 3, (4) in the semiconductor laser pumped solid-state laser device of any one of configurations 1 to 3, The member has a configuration in which a reflecting surface is formed on a conical surface that shares a central axis with the solid-state laser medium. .

[0010]

According to the above configuration 1, the exciting laser light incident on the reflecting surface of the reflecting member is reflected back and forth a plurality of times while passing through the solid-state laser medium between the facing reflecting surfaces of the reflecting member. As a result, the solid-state laser medium can sufficiently absorb the excitation laser light that has entered the reflecting surface of the reflecting member. Moreover, since the reflection surface of the reflecting member can secure a sufficiently large area where the excitation laser light can be incident, a large amount of excitation laser light can be incident from a large number of excitation semiconductor laser devices. It can be absorbed in a solid-state laser medium. Therefore, a strong oscillation laser beam can be obtained while maintaining high pumping efficiency.

Further, according to the configuration 2, since a part of the exciting laser light is made incident also from the end face, it becomes possible to obtain a laser light of higher output.

Further, according to the configuration 3, it becomes possible to relatively easily enter a large amount of laser light for excitation into the solid-state laser medium.

Further, according to the structure 4, the pumping laser light emitted from the pumping semiconductor laser device can be made to enter the solid-state laser medium more efficiently.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment FIG. 1 is a longitudinal sectional view of a semiconductor laser pumped solid-state laser device according to a first embodiment of the present invention, and FIG. 2 is an optical path explanatory view of the first embodiment. Hereinafter, the first embodiment of the present invention will be described in detail with reference to these drawings.

1 and 2, reference numeral 1 is a solid-state laser medium, reference numeral 2 is a pumping semiconductor laser device, reference numeral 3a,
Reference numeral 3b is a plate-shaped reflecting mirror that constitutes a reflecting member, reference numeral 4 is a total reflection mirror, reference numeral 5 is an output mirror, and reference numeral 6 is a collimating lens. The total reflection mirror 4 and the output mirror 5 form a laser resonator.

The total reflection mirror 4 and the output mirror 5 have an optical axis in common with the central axis (hereinafter referred to as an optical axis) of the solid-state laser medium 1, and a predetermined distance is provided on both sides of the solid-state laser medium 1. It is arranged. The reflecting mirrors 3a and 3b are arranged so as to sandwich the solid-state laser medium 1. In this case, the reflecting mirror 3b is arranged so that its reflecting surface is in close contact with and parallel to the side surface of the solid-state laser medium 1, while the reflecting mirror 3a forms an angle θ with the solid-state laser medium. It is arranged.

The pumping semiconductor laser device 2 has a solid laser medium 1 whose optical axis is outside the reflecting mirrors 3a and 3b.
Is arranged in parallel to the optical axis of the optical disc, separated from the optical axis by a predetermined distance, and intersects the reflecting mirror 3a at an angle θ.
Further, in front of the pumping semiconductor laser device 2, a collimating lens 6 for arranging the pumping laser light L ₀ emitted from the pumping semiconductor laser device 2 into parallel light is arranged. Therefore, the excitation laser light L ₀ emitted from the excitation semiconductor laser device 2 is collimated through the collimator lens 6 and then incident on the reflecting mirror 3a.

Here, the solid-state laser medium 1 is doped with Nd ions, which is a laser active material, in an amount of 1.1 atom%, and has a wavelength of 10
It is a slab laser of Nd: YAG that oscillates a laser beam of 64 nm, has a length of 30 mm, a width of 2 mm, and a thickness of 1 mm, and has a light absorption peak wavelength of 809 nm.

Here, the total reflection mirror 4 is one in which the radius of curvature of the concave surface which is the total reflection surface is set to 5 m. Further, the output mirror 5 forms a reflection film made of a dielectric multilayer film on the surface of the concave surface of a glass body having a concave lens shape arranged so that the concave surface faces the laser medium 2 side, and the output laser light L ₁ The transmittance is set to 3%, and by setting the radius of curvature of the concave surface to 5 m, the total reflection mirror 4 constitutes a laser resonator having a resonator length of 100 mm.

The pumping semiconductor laser device 2 is a GaAs type semiconductor laser device having an oscillation wavelength of 800 to 820 nm and an output of 500 mW. This pumping semiconductor laser device 3 has an oscillation wavelength that coincides with the absorption peak of the solid-state laser medium 2 when the temperature is kept at 25 ° C. 809
nm.

The reflecting mirrors 3a and 3b have surfaces facing each other as reflecting surfaces, and are, for example, glass plates plated with gold, silver or aluminum.

Now, as shown in FIG. 2, the excitation laser light L made into parallel light by the collimator lens 6.
₀ enters the reflecting surface of the reflecting mirror 3a at an angle θ, and thereafter passes through the solid-state laser medium 1 while repeating reflection between the reflecting mirrors 3b and 3a, and is absorbed and excited. In this case, the incident angle when the light is first incident on the reflecting surface of the reflecting mirror 3a is (π
/ 2-θ), and the angle of incidence on the reflecting surface of the reflecting mirror 3b is (π / 2-2θ). After that, the incident angle becomes smaller by θ each time it is reflected. From this relationship, the value of θ to be set so that the excitation laser light passes through the solid-state laser medium 1 n times can be obtained.
For example, in the example shown in FIG. 2, the pumping laser beam L ₀ is reciprocated 3 times between the reflecting mirrors 3a and 3b, and the solid-state laser medium 1 is passed 6 times, but in this case, it is the 4th time. Θ may be set to 22.5 ° so that the angle of incidence (π / 2-4θ) on the reflecting mirror is 0 °. Further, in the case of making five round trips, the incident angle (π / 2−
Θ = 15 ° may be set so that (6θ) becomes 0 °. Here, how many times the excitation laser beam L ₀ is absorbed in the solid-state laser medium 1 is determined by
Although depending on the thickness and the absorptivity of the solid-state laser medium 1, in the case of this embodiment, the exciting laser beam L ₀ has an absorptance of 95% absorption when passing through the solid-state laser medium 1 for a distance of 6 mm. In addition, since the thickness is 1 mm,
As shown in FIG. 2, the reflectors 3a and 3b are reciprocated 3 times and passed 6 times. As a result, most of the excitation laser light L ₀ emitted from the excitation semiconductor laser device 2 and incident on the reflecting mirror 3 a is in the solid-state laser medium 1.
Is absorbed by and converted into excitation energy.

According to the above configuration, the wavelength is 1064 nm.
Thus, the absorption efficiency when obtaining the output laser light L ₁ having an output of 120 mW can be set to 90% or more. Incidentally, in the conventional side-pumped semiconductor laser pumped solid-state laser device, the absorption efficiency at the time of obtaining an oscillated laser beam of similar output was 70% or less.

Second Embodiment FIG. 3 is a perspective view of a semiconductor laser pumped solid state laser device according to a second embodiment of the present invention, and FIG. 4 is a vertical sectional view of the second embodiment. The second embodiment will be described in detail below with reference to FIGS. 3 and 4. Since most of the configuration of this embodiment is the same as that of the above-described first embodiment, the common parts are denoted by the same reference numerals and the description thereof is omitted, and only the points unique to this embodiment will be described below. Will be explained.

In this embodiment, the angle formed by the reflecting mirrors 3a and 3b facing each other in the first embodiment with respect to the solid-state laser medium 1 is changed so that both the reflecting mirrors 3a and 3b are θ / θ with respect to the solid-state laser medium 1. 2 and the reflectors 3
The same reflecting mirrors 3c and 3d are arranged on both sides of a and 3b, and further, two sets of pumping semiconductors for making the pumping laser light L ₀ enter the reflecting surfaces of the reflecting mirrors 3a and 3b at the incident angle α. The laser device 2 and the collimator lens 6 are provided. The other structure and the optical components used are the same as in the first embodiment.

Now, as shown in FIG. 4, the excitation laser beam L made into a parallel beam by the collimator lens 6.
₀ enters the reflecting surfaces of the reflecting mirrors 3a and 3b at an angle α, and thereafter passes through the solid-state laser medium 1 while being repeatedly reflected between the reflecting mirrors 3b and 3a, and is absorbed and excited. In this case, the incident angle becomes smaller by θ each time it is reflected by the reflecting surfaces of the reflecting mirrors 3a and 3b. Therefore, as in the first embodiment, the value of θ that should be set so that the excitation laser light passes through the solid-state laser medium 1 n times can be obtained from this relationship. For example, in order to make the excitation laser beam L ₀ reciprocate 3 times between the reflecting mirrors 3a and 3b and pass the solid-state laser medium 1 6 times, as in the first embodiment, the incident angle (α Α and θ are determined so that −4θ) becomes 0 °. Here, the number of reflection round trips can be increased by increasing the incident angle α and decreasing θ, but when θ is decreased, the beam width of the excitation laser beam L ₀ emitted from the excitation semiconductor laser device 2 is increased. If it is wide, it becomes difficult to make the entire beam incident on the reflecting mirror, so the values of α and θ are selected in consideration of such points.

The reflecting mirrors 3c and 3d are arranged so that the pumping laser light reflected or scattered in the lateral direction is incident on the solid-state laser medium 1, but of course, two more sets of pumping semiconductor laser devices are provided. According to the above-mentioned configuration, a more powerful output laser beam can be obtained by making a pumping laser beam enter the reflecting mirrors 3c and 3d in the same manner from the direction α described above by using a collimator lens. , Output of 200 mW with the same excitation efficiency as the first embodiment
The output laser light L ₁ can be obtained.

Third Embodiment FIG. 5 is a perspective view of a semiconductor laser pumped solid-state laser device according to a third embodiment of the present invention, and FIG. 6 is a vertical sectional view of the third embodiment. The third embodiment will be described in detail below with reference to FIGS. Since this embodiment also has a part in common with the above-described second embodiment, the common parts are designated by the same reference numerals, and the description thereof will be omitted. Only the points peculiar to this embodiment will be described below. explain.

In this embodiment, a conical reflecting mirror 33 is used in place of the four reflecting mirrors 3a, 3b, 3c, 3d in the above-mentioned second embodiment, and a slab type is used as a solid-state laser medium. A solid-state laser medium 31 that is a cylindrical laser rod is used, and a selective reflection film 34 formed on the end face of the solid-state laser medium 31 is used instead of the total reflection mirror 4, and an exciting semiconductor is used without using a collimator lens. The laser device 2 is arranged directly on the optical axis of the solid-state laser medium 31.

The conical reflecting mirror 33 cuts the inside of a cylindrical body into a truncated cone shape and penetrates the top of the truncated cone to form a light passing portion, and the surface of the remaining conical surface is made of gold, silver or aluminum. A reflecting film is formed by plating such as the above to form a reflecting surface.

The solid laser medium 31 is arranged inside the conical reflecting mirror 33 along the central axis. The solid-state laser medium 31 has a cylindrical Nd: YAG whose side surface is polished.
It is a laser rod.

The selective reflection film 34 is formed on one end face of the solid-state laser medium 31, which intersects with the optical axis, that is, on the left end face in the drawing.
Is deposited. The selective reflection film 34 constitutes a laser resonator together with the output mirror 5, and has a high reflectance of 99.9% or more with respect to the output laser light (L ₁ = 1064 nm), while being excited. Laser light (L ₀ = 80
It has a property of transmitting 85% or more of 7 nm). Although not shown, the other end face of the solid-state laser medium 32, that is, the right end face in the figure, is provided with a non-reflective coating, and the reflectance with respect to the output laser light L ₁ at this end face is 0.5% or less. It is supposed to be.

The pumping semiconductor laser device 2 is arranged such that the light emitting portion faces the solid-state laser medium 31 and is located on the optical axis, and the pumping laser light L ₀ emitted from the light emitting portion is emitted. The light is directly incident on the reflecting surface of the conical reflecting mirror 33.

Here, the apex angle of the conical reflecting mirror 33 is θ / 2.
Then, this apex angle is determined according to the emission angle β of the excitation semiconductor laser device 2. That is, as in the first and second embodiments, the incident angle at which L ₀ of the exciting laser light is incident on the reflecting surface at the n-th time is [π / 2-β- (n-1 / 2).
[theta]], and if the number of reflections n is obtained from the characteristics and size of the solid-state laser medium used, then [theta] can be obtained from this.

For example, when Nd: YAG with a diameter of 1 mmφ is used as the solid-state laser medium 31 and the excitation semiconductor laser device 2 has an emission angle of 20 °, four reflections are required. From this, it is understood that θ / 2 = 10 ° may be set so that the angle of incidence on the reflecting surface for the fourth time is 0 °.

According to this embodiment, the exciting laser light L ₀ emitted from the exciting semiconductor laser device 2 is directly condensed by the conical reflecting mirror without using a collimator lens or the like, and is condensed on the solid-state laser medium 31. I am trying to make it incident. Therefore, as the excitation semiconductor laser device 2, it is possible to use an excitation light source having a wide light emitting surface such as a semiconductor laser array, which is difficult to focus by a collimator lens or the like. Further, since one of the mirrors forming the laser resonator is formed of the selective reflection film 34, a part of the pumping laser light L ₀ emitted from the pumping semiconductor laser device 2 is also partially exposed from the end face of the solid-state laser medium 31. It is possible to make the light incident, and it is possible to improve the excitation efficiency accordingly.

In the above embodiment, an example in which one pumping semiconductor laser device 2 is used is given. However, as shown in FIG. A strong oscillation laser beam L ₁ can be obtained. Further, as shown in FIG. 8, if the conical reflecting mirror 31 is arranged in the opposite direction and the excitation laser light L ₀ from the excitation semiconductor laser device 2 is made incident from the output mirror 5 side, The device can also be made smaller.

Further, as the conical reflecting mirror 33, in addition to the examples given in the above embodiments, as shown in FIGS. 9 and 10, a transparent member such as synthetic quartz glass is formed into a truncated cone shape. The main body 43a may be used as the main body 43a, and the reflection mirror 43 may be used in which the reflection film 43b is formed on the outer peripheral conical surface of the main body 43a and the solid laser medium storage hole 43c is provided along the central axis of the main body 43a. By using this reflecting mirror 43, it becomes easy to hold the solid-state laser medium 31, and
The solid laser medium 31 is brought into thermal contact with the main body portion 43a in the solid laser medium storage hole 43c to facilitate the heat dissipation of the solid laser medium 31.

In the above-mentioned embodiment, the Nd: YAG rod is used as the solid-state laser medium, but the solid-state laser medium includes Nd: YLF and Nd: gl.
ass, Er: YAG, Er: YLF, Er: glass
You may use s etc. In that case, it is needless to say that conditions such as a laser resonator should be selected according to each laser medium.
In addition, a semiconductor laser device for excitation is also, for example, InGa.
P, AlGaAs, GaAsP or a semiconductor laser array may be used.

[0040]

As described in detail above, in the semiconductor laser pumped solid-state laser device according to the present invention, the reflecting surface is provided around the solid-state laser medium so as to face the solid-state laser medium and to form a predetermined angle with each other. A reflecting member is provided, and at least a part of the exciting laser light emitted from the exciting semiconductor laser device is incident on the reflecting surface of the reflecting member, and the exciting laser light is opposite to the reflecting surface of the reflecting member. It is characterized in that it is reflected multiple times while passing through the solid-state laser medium in between, while absorbing the excitation laser light in the solid-state laser medium while being reflected back, and is excited in the reflecting member A large amount of laser light for excitation can be made incident by adopting a structure in which the laser light for excitation is made incident, which enables high excitation efficiency with a relatively simple structure. In which made it possible to obtain a laser beam having a lifting and while high output.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a semiconductor laser pumped solid-state laser device according to a first embodiment of the present invention.

FIG. 2 is an optical path diagram of the semiconductor laser pumped solid-state laser device according to the first embodiment of the present invention.

FIG. 3 is a perspective view showing a configuration of a semiconductor laser pumped solid-state laser device according to a second embodiment of the present invention.

FIG. 4 is a vertical sectional view of a semiconductor laser pumped solid-state laser device according to a second embodiment of the present invention.

FIG. 5 is a perspective view showing a configuration of a semiconductor laser pumped solid-state laser device according to a third embodiment of the present invention.

FIG. 6 is an optical path diagram of a semiconductor laser pumped solid-state laser device according to a third embodiment of the present invention.

FIG. 7 is a view showing a modified example of the semiconductor laser pumped solid-state laser device according to the third embodiment of the present invention.

FIG. 8 is a diagram showing a modification of the semiconductor laser pumped solid-state laser device according to the third embodiment of the present invention.

FIG. 9 is a perspective view of a modified example of the conical reflecting mirror.

FIG. 10 is a cross-sectional view of a modified example of the conical reflecting mirror.

[Explanation of symbols]

1, 31 ... Solid-state laser medium, 2 ... Excitation semiconductor laser device, 3a, 3b ... Reflecting mirror constituting reflecting member, 4 ... Total reflection mirror, 5 ... Output mirror, 6 ... Collimator lens, 3
3 ... Conical reflector, 34 ... Selective reflection film, 43 ... Reflector

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[Procedure amendment]

[Submission date] September 18, 1991

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

Claims (4)

[Claims] 1. A solid-state laser medium disposed in a laser resonator is irradiated with laser light for excitation emitted from an excitation semiconductor laser device, and the solid-state laser medium is excited to obtain output laser light. In the semiconductor laser pumped solid-state laser device described above, a reflection member is provided around the solid-state laser medium, the reflecting member facing the solid-state laser medium and having reflecting surfaces forming a predetermined angle with each other, the pumping semiconductor laser device While making at least a part of the exciting laser light emitted from the reflecting surface of the reflecting member, the exciting laser light is passed a plurality of times while passing through the solid-state laser medium between the facing reflecting surfaces of the reflecting member. A semiconductor laser pumped solid-state laser device characterized by being reflected back. 2. The semiconductor laser pumped solid-state laser device according to claim 1, wherein a part of the pumping laser light emitted from the pumping semiconductor laser device serves as an entrance / exit surface of a resonant laser light of a solid-state laser medium. A semiconductor laser pumped solid-state laser device characterized in that the light is incident from the end face. 3. The semiconductor laser pumped solid-state laser device according to claim 1, wherein a semiconductor laser array is used as the pumping semiconductor laser device. 4. The semiconductor laser pumped solid-state laser device according to claim 1, wherein the reflecting member has a reflecting surface formed on a conical surface sharing a central axis with the solid-state laser medium. A semiconductor laser pumped solid-state laser device characterized by: