JPH07112085B2 - Array semiconductor laser pumped solid-state laser device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an array semiconductor laser pumped solid-state laser device that optically couples outputs of an array semiconductor laser as a pumping light source with high efficiency to optically pump a solid-state laser element. .

[Prior Art] Solid-state lasers using a semiconductor laser as an excitation light source are attracting attention because they can achieve high efficiency, long life, and miniaturization. In particular, in the end-face excitation method in which the solid-state laser is optically excited from the optical axis direction (see, for example, Japanese Patent Laid-Open No. 58-52889), the excitation space by the semiconductor laser output light is well matched to the oscillation mode of the solid-state laser to achieve high efficiency. Basic transverse mode oscillation can be realized.

Since the semiconductor laser has a large beam divergence angle, it is necessary to dispose the condensing system close to the semiconductor laser for condensing.
It is not easy to collect oscillation light.

In order to increase the output of a semiconductor laser pumped solid-state laser, it is necessary to increase the output of a semiconductor laser for pumping. In a semiconductor laser, laser light is extracted from the stripe-shaped active layer, but the output from a single stripe is limited, so
In order to further increase the output, it is necessary to form an array in which a plurality of stripes are arranged.

[Problems to be Solved by the Invention] When such an array semiconductor laser is used as a pumping light source, the length of the array is about 1 cm, so that a plurality of beams are formed into one spot by using a normal lens system. Since it is impossible to narrow down, it is not possible to adopt the end face excitation method with good excitation efficiency, and it can be applied only to the side surface excitation method (see, for example, Japanese Patent Application Laid-Open No. 1-107587).

The present invention has been made in view of the above circumstances, and condenses a plurality of beams with a large divergence angle emitted from a multi-striped array semiconductor laser so as to match the spatial mode of oscillation of the solid-state laser, and efficiently solid-state laser. An object of the present invention is to provide a semiconductor laser pumped solid-state laser capable of generating output light.

[Means for Solving the Problems] In order to achieve the above-mentioned object, in the array semiconductor laser pumped solid-state laser of the present invention, the light for condensing and synthesizing two array semiconductor laser outputs to optically pump the solid-state laser element is used. Collimating for collecting and collimating the output light of the first array semiconductor laser by arranging distributed refractive index lenses as couplers corresponding to each stripe of the first array semiconductor laser with sandwiching a polarization beam splitter. An array distributed index lens used as a lens, and an aspherical lens used as a focusing lens for collectively focusing and collimating the respective striped light beams collimated by the lens and exciting the solid-state laser element on the end face thereof are used. A second array portion which is arranged in series and focuses the second array semiconductor laser on the second light receiving surface to the polarization beam splitter. A cloth refractive index lens was placed.

In the above array semiconductor laser pumped solid-state laser, an array semiconductor laser stack is formed by stacking a plurality of array semiconductor laser parts in the thickness direction, and the same number of array distributed refractive index lens parts are provided according to each array semiconductor laser stack. The stacked array gradient index lens was replaced.

[Operation] The lateral mode characteristics of the semiconductor laser pumped solid-state laser are determined by the shape of the optical pumping space in the solid-state laser element in the case of the end-face pumping method. Therefore, in order to obtain the fundamental transverse mode, the intensity distribution of the narrowed excitation light should be as close as possible to the Gaussian distribution,
It is desirable to stably create a beam spot of a certain size in the solid-state laser device.

A semiconductor laser light with a large divergence angle is obtained by using a distributed index lens, which is an optical glass body having a refractive index distribution in which the refractive index gradually decreases from the central axis toward the outer peripheral surface, as an optical coupler of a semiconductor laser pumped solid-state laser. Can be easily collected. By utilizing the fact that the laser light from each stripe can be condensed by using this distributed index lens, the light emitted from each stripe of the array semiconductor laser is condensed by the array distributed index lens and no spherical aberration occurs. High-quality fundamental transverse mode light can be obtained by narrowing the total light into one beam spot with an aspherical lens and exciting the solid-state laser element. Further, by utilizing the fact that the reflection and transmissivity at oblique incidence of light at the interface depend on the polarization, two semiconductor laser lights polarized at right angles to each other are beam-combined using a polarization beam splitter and easily excited. The light intensity can be doubled. Further, by using an array semiconductor laser stack in which a plurality of array semiconductor lasers are stacked in the thickness direction and an array distribution ratio lens corresponding thereto, an even stronger excitation light intensity can be obtained.

[Examples] In order to further clarify the features and advantages of the present invention, a detailed description will be given based on examples.

FIG. 1 is a schematic diagram of an array semiconductor laser pumped solid-state laser that collects and synthesizes two array semiconductor laser lights and pumps a solid-state laser element at an end face. As shown in Figure 1,
Nd: YAG laser element 5 is used as a solid-state laser element, and one end face is dichroic coated (Nd: YAG laser oscillation wavelength is 1064 nm for high reflection (HR), array semiconductor laser light wavelength is for 808 nm and high transmission (AR)). Plane as the excitation plane,
A solid-state laser resonator is configured with the output mirror 6. In order to combine beams emitted from the two array semiconductor lasers 1a and 1b for excitation, the polarization beam splitter 3 is used as a beam combiner by utilizing the fact that the array semiconductor laser beams are polarized, and the arrows 7a, As shown in, the oscillation light from the first array semiconductor laser 1a is polarized parallel to the paper surface, and the second array semiconductor laser 1a
The oscillated light from 1b is polarized perpendicularly to the paper surface, is condensed by the first and second array distributed index lenses 2a and 2b, respectively, and is combined into a beam. The beam spot focused by the aspherical lens 4 is solidified. Nd: YAG laser element 5 which is a laser element
Get inside. The polarization of one array semiconductor laser beam can be matched with the other by inserting a half-wave plate between the array semiconductor laser and the polarization beam splitter 3. This is convenient when you want to avoid spatial interference. The array semiconductor lasers 1a and 1b used consist of an array in which 20 active layer stripes 9a and 9b each having a width of 100 μm are arranged at intervals of 500 μm. Distributed index lens as condenser lens array
2a and 2b are each a distributed index lens 2 with a width of 500 μm.
The light emitted from each of the 20 stripes 9a and 9b is collected and collimated. In the array semiconductor laser pumped solid-state laser pumped in this way,
Array semiconductor laser light (wavelength 808nm) output at 10W Nd: YAG
The fundamental transverse mode oscillation light 8 of the laser (wavelength 1064 nm) is obtained at a high output of 3 W through the output mirror 6.

FIG. 2 is a schematic diagram of an array semiconductor laser pumped solid-state laser that collects and oscillates the oscillated light of two array semiconductor laser stacks and pumps the end face of the solid-state laser element. The array semiconductor laser stacks 10a and 10b used are the two array semiconductor lasers described in the embodiment of FIG. 1 stacked at 300 "m intervals in the thickness direction. Array distributed index lens stacks 11a and 11b as a condenser lens array are arranged such that the above array distributed index lenses have an array semiconductor laser stack 10 in which the center axes of the upper and lower lenses are arranged.
Two semiconductor laser active layer stripes 13 a and 10 b are stacked to match the vertical spacing of 300 m.
Each of the light emitted from a and 13b is collected and collimated. Hereafter, in the array semiconductor laser pumped solid-state laser device that was end-pumped in the same way as in FIG. It is obtained with high output.

In the embodiment of the present invention, Nd: Y is used as the solid-state laser device.
Although an AG laser is used, it is not limited to this. Needless to say, an array semiconductor laser having a wavelength matched to the maximum absorption wavelength is used with the change of the solid-state laser element. Both surfaces of the lens and the polarizing beam splitter are coated with an antireflection coating at the array semiconductor laser wavelength. Further, the number of stages of the array semiconductor laser stack and the array distributed index lens stack in the second embodiment is not limited to two.

[Effects of the Invention] As described above, a semiconductor laser pumped solid-state laser having such a configuration as an optical coupler enables end face pumping, which was difficult with an array semiconductor laser, and is small in size, high in efficiency, high in beam quality, and high in output. A solid-state laser can be realized.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an array semiconductor laser pumped solid-state laser that collects and synthesizes two array semiconductor laser lights and pumps a solid-state laser element at an end face. FIG. 2 shows oscillation of two array semiconductor laser stacks. FIG. 3 is a schematic view of an array semiconductor laser pumped solid-state laser that collects and synthesizes light and pumps a solid-state laser element at an end face. In the figure. 1a: Array semiconductor laser (top view) 1b: Array semiconductor laser (side view) 2a, 2b: Array distributed index lens 3: Polarizing beam splitter 4: Aspherical lens 5: ND: YAG laser element 6: Output mirror 7a , 7b: Polarization direction 8: Solid-state laser output light 9a, 9b :: Semiconductor laser active stripe 10a: Array semiconductor laser stack (top view) 10b: Array semiconductor laser stack (side view) 11a, 11b: Array distributed index lens stack 12: Solid-state laser output light 13a, 13b: Semiconductor laser active layer stripe

Claims (2)

[Claims] 1. A distributed refractive index lens is provided in each of the first array semiconductor lasers with a polarization beam splitter interposed therebetween as an optical coupler for collecting and synthesizing two array semiconductor laser beams to optically excite a solid-state laser element. An array distributed index lens used as a collimating lens for collecting and collimating the output light of the first array semiconductor lasers arranged corresponding to the stripes, and the respective striped light collimated thereby are collectively collected. An aspherical lens used as a focusing lens for illuminating and superimposing on one point to excite the end face of the solid-state laser element is arranged in series, and the second array semiconductor is provided on the second light receiving surface to the polarization beam splitter. An array semiconductor laser pumped solid-state laser device comprising a second array distributed index lens for condensing laser light. 2. An array semiconductor laser pumped solid-state laser device according to claim 1, wherein each array semiconductor laser section is an array semiconductor laser stack in which a plurality of array semiconductor lasers are stacked in a thickness direction, and each array is arranged. An array semiconductor laser pumped solid-state laser device characterized in that an array distributed index lens stack in which the same number of array distributed index lens portions are stacked at the same step interval according to the semiconductor laser stack is arranged.