A beam combining laser device and beam combining method thereof

Abstract

The invention discloses a beam combining laser device and a beam combining method thereof, comprising a plurality of laser lenses and a laser source coaxially arranged in series, wherein the laser lens has two pairs of light-transmitting surfaces, and the two pairs, or four light-transmitting surfaces, are arranged oppositely in the X-axis and Y-axis directions, respectively; the laser emitted by the laser source is incident from the transmission surface of the laser lens in the Y-axis; the refractive index of the laser lens in the X-axis direction is a gradient refractive index, and the refractive index in the Y-axis direction is constant; the gradient refractive index is a gradient refractive index that gradually changes from a transmission surface at one end of the laser lens in the X-axis direction to a transmission surface at the other end, from low to high; the laser incident from the transmission surface on one side of the Y-axis is gradually deflected under the action of the gradient refractive index; when the laser deflects and reaches the transmission surface on the other side of the X-axis, it is bent at a 90-degree angle and emitted in a straight line; wherein: the laser deflected in the laser lens connected in series after the starting end laser lens to form a 90-degree bend is emitted in a straight line after being emitted in a straight line with the previous adjacent laser lens through the laser beam combination to form a beam-combined laser.

Description

Technical Field

[0001] The invention relates to a beam combining laser device and a beam combining method thereof. Background Art

[0002] In order to obtain high laser power, in addition to using high-power laser source devices, laser beam combining can also be used to combine the lasers emitted by multiple low-power laser sources to form a high-power laser beam. This is currently a common way to obtain high-power beams. However, the beam combining methods in the prior art all have a "step" design, that is, there is a spacing in the direction of the beam stacking, and there are upper and lower step spacings in the arrangement of the light sources. If this step spacing is cancelled, since the surface of the reflector is coated with a high reflectivity film, the light will encounter other reflectors after being deflected by the reflector by 90°. The "reflector blocks the light" situation, and the beam combining effect is greatly reduced, and the complete beam combining cannot be completed. Even if the reflector blocking is not considered, when the light source is designed to be arranged front and back, the light source in front will still block the light source behind. This limitation is essentially due to the fact that there is always a physical entity in the optical device, and the entity will always block the light, which means that stacking more beams (for the purpose of obtaining higher power) will deteriorate the beam quality.

[0003] As a further explanation, if fiber coupling is performed, the more stacked beams there are, the larger the fiber input NA and output NA. In other words, the larger the output beam divergence angle, the faster the energy density will decrease during transmission (similar to poor beam quality, the industry also calls this concept "brightness" difference). At the same time, due to the limitation of fiber NA, this will greatly limit the number of stacked beams, limit the total power and power density of semiconductor lasers, and this is the bottleneck of semiconductor laser (also known as "pump source" and "fiber-coupled semiconductor laser") design. Summary of the invention

[0004] In view of the above problems, the purpose of the present invention is to provide a beam combining laser device and a beam combining method thereof, which adopts a uniaxial gradient refractive index laser lens. Under the premise of achieving superimposed beams (higher power), the system beam quality will not deteriorate. In theory, an unlimited number of beams can be superimposed to obtain a laser beam with a higher energy density.

[0005] In order to achieve the above object, the scheme of the present invention is:

[0006] A beam combining laser device comprises a plurality of laser lenses and laser sources arranged in series, wherein at least one laser source is arranged corresponding to one laser lens, wherein: the laser lens has two pairs of light-transmitting surfaces, the two pairs, four light-transmitting surfaces are arranged opposite to each other in the Y-axis and X-axis directions of the laser lens, respectively, the height of the light-transmitting surfaces is the Z-axis of the laser lens, the plurality of laser lenses are coaxially arranged in series along the X-axis direction, the laser emitted by the laser source is perpendicular to the X-axis of the laser lens and is injected from the transmission surface at one end of the Y-axis of the laser lens, the refractive index of the laser lens in the X-axis direction is a gradient refractive index, the refractive index in the Y-axis and Z-axis directions is constant, and the gradient refractive index is a gradient refractive index that gradually changes from a transmission surface at one end of the X-axis of the laser lens to a transmission surface at the other end, The laser of the laser source is incident from the Y-axis transmission surface at one end side of the X-axis of the laser lens, that is, the low refractive index end side. Under the action of the X-axis gradient refractive index, the incident laser is gradually deflected toward the other end side of the X-axis, that is, the high refractive index side. When the laser deflects and reaches the other end transmission surface with a high refractive index of the X-axis, it forms a 90-degree bend and is emitted in a straight line. The constant refractive index of the Y-axis causes the laser incident from the end transmission surface with a low refractive index of the X-axis to penetrate the laser lens in a straight line, wherein: the laser deflected to form a 90-degree bend in the laser lens connected in series after the starting end laser lens is emitted in a straight line after passing through the laser beam to form a combined laser with the previous adjacent laser lens and then emitted in a straight line.

[0007] A further solution is: the laser lens is a rectangular laser lens with two pairs of adjacent light-transmitting surfaces in the X-axis and Y-axis directions being perpendicular to each other.

[0008] The solution is further as follows: when the gradient refractive index is determined and the position of the laser entrance point in the X-axis direction is determined, the X-axis length and Y-axis length of the laser lens are lengths that ensure that the laser incident on the transmission surface on one side of the Y-axis is gradually deflected under the action of the gradient refractive index, and when the laser deflects and reaches the transmission surface on the other end with a high refractive index on the X-axis, it forms a 90-degree curved straight line and is emitted.

[0009] A further solution is: there are two laser sources, and the two laser sources are arranged opposite to the transmission surface at two ends of the Y axis of the laser lens.

[0010] The solution is further that: when the laser deflects and reaches the other end transmission surface with a high refractive index on the X-axis, it forms a 90-degree curved straight line and the emission point is the center point of the transmission surfaces on both ends of the X-axis of the laser lens.

[0011] A further solution is that the four light-transmitting surfaces of the laser lens are respectively coated with high-transmittance films.

[0012] The solution is further as follows: a fast-axis collimator and a slow-axis collimator are arranged in series between the laser source and the laser lens by adjusting the positioning bracket, with the fast-axis collimator being in front and the slow-axis collimator being in the back.

[0013] A further solution is that the laser source is a semiconductor laser chip.

[0014] A beam combining method for a beam combining laser includes the beam combining laser device, wherein: the laser lens is a rectangular laser lens with two pairs of adjacent light transmission surfaces perpendicular to each other in the X-axis and Y-axis directions, a fast axis collimator and a slow axis collimator are arranged in series between the laser source and the laser lens by adjusting a positioning bracket, and the laser emitted from the laser source sequentially passes through the fast axis collimator and the slow axis collimator and then enters the laser lens from the Y-axis transmission surface of the laser lens. The beam combining method includes:

[0015] The first step is to set a debugging laser transmitter to emit a debugging laser, and the debugging laser is injected from the X-axis low refractive index end side of the laser lenses coaxially arranged in series along the X-axis direction and passes straight through;

[0016] The second step is to turn on the laser source corresponding to each laser lens respectively, and observe it using a CCD photodetector. By adjusting the position of the laser source, the fast-axis collimator, and the slow-axis collimator corresponding to each laser lens, the laser incident from the Y-axis transmission surface is bent at a 90-degree angle when it deflects and reaches the other end transmission surface with a high refractive index on the X-axis, and then combined with the debugging laser passing through to form a combined laser and then emitted in a straight line;

[0017] The third step is to fix the laser source, fast-axis collimator and slow-axis collimator at the determined position, remove the debugging laser transmitter, and complete the beam combining.

[0018] The solution is further as follows: there are two laser sources, and the two laser sources are arranged corresponding to the transmission surfaces on both sides of the Y-axis of the laser lens. When the laser is deflected and reaches the other end transmission surface with a high refractive index on the X-axis, it forms a 90-degree curved straight line and the emission point is the center point of the transmission surfaces at both ends of the X-axis of the laser lens.

[0019] The beneficial effect of the present invention is that the beam quality will not deteriorate under the premise of achieving superposition of beams (higher power) by using a uniaxial gradient refractive index laser lens. In theory, an unlimited number of beams can be superimposed to obtain a laser beam with a higher energy density. In actual engineering applications, due to the limitations of material thermal stability and coating damage threshold, existing engineering capabilities cannot achieve the effect of unlimited superposition. Even so, this solution can still break through the existing design bottleneck.

[0020] The present invention is described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the structure plane of the present invention;

[0022] Figure 2 It is a schematic diagram of the structural axial side of the present invention;

[0023] Figure 3 It is a schematic diagram of the refractive index variation curve along the X axis;

[0024] Figure 4 It is a schematic diagram of the refractive index change curve along the Y axis and the Z axis. DETAILED DESCRIPTION

[0025] Embodiment 1:

[0026] A beam combining laser device, such as Figure 1 , Figure 2 Figure 3 and Figure 4 As shown, the beam combining laser device includes a plurality of laser lenses 1 and laser sources 2 arranged in series with each other, and the plurality of laser lenses 1 and laser sources 2 arranged in series with each other are positioned on a support frame (not shown in the figure), and the support frame is different according to different purposes of use. At least one laser source 2 is arranged corresponding to one laser lens 1, wherein: the laser lens is a three-dimensional lens with length, width and height, and the laser lens has two pairs of light-transmitting surfaces, and the two pairs, four light-transmitting surfaces are arranged relatively in the X-axis (length) and Y-axis (width) directions of the laser lens which are perpendicular to each other, and the height of the light-transmitting surface is the Z-axis of the laser lens, as shown in FIG. Figure 1 and Figure 2 As shown, a plurality of laser lenses 1 are coaxially arranged in series along the X-axis (length) direction, and the laser 201 emitted by the laser source 2 is incident from the transmission surface 101 at one end of the Y-axis of the laser lens. The refractive index of the laser lens in the X-axis direction is a gradient refractive index, and the refractive index in the Y-axis and Z-axis directions ( Figure 1The refractive index of the lens (vertical to the paper surface) is constant, and the gradient refractive index is a gradient refractive index that gradually changes from low to high at least from one end of the X-axis to the other end of the transmission surface. The laser of the laser source is incident on the X-axis end side of the laser lens, that is, the low refractive index end side, from the Y-axis end transmission surface 101. Under the action of the X-axis gradient refractive index, the incident laser is gradually deflected toward the other end side of the X-axis, that is, the high refractive index side, and when the laser deflects to the other end transmission surface with a high refractive index on the X-axis, it forms a 90-degree curved straight line for emission; the determination of the gradient refractive index of the laser lens must satisfy that the laser incident from the transmission surface on one side of the Y-axis is gradually deflected toward the other end side with a high refractive index on the X-axis under the action of the gradient refractive index, and when the laser deflects to the other side transmission surface 102 with a high refractive index on the X-axis, it forms a 90-degree curved straight line for emission. The determination of the gradient refractive index of the laser lens must satisfy that the laser incident from the transmission surface on one side of the Y-axis is gradually deflected toward the other end side with a high refractive index on the X-axis under the action of the gradient refractive index, and when the laser deflects to the other side transmission surface 102 with a high refractive index on the X-axis, it forms a 90-degree curved straight line for emission. The laser beam is emitted in a straight line, that is, the position of the incident laser beam in the X-axis direction is just the position where the laser beam is deflected to the transmission surface 102 at the other end of the X-axis, and the Y-axis (and Z-axis (along the paper direction)) has a constant refractive index, so that the laser beam incident from the transmission surface at the end with a low refractive index of the X-axis penetrates the laser lens in a straight line, wherein: the laser beam deflected to form a 90-degree angle bend in the laser lens connected in series after the starting end laser lens is emitted in a straight line with the previous adjacent laser lens, passes through the laser beam to form a combined beam laser 3, and then is emitted in a straight line; wherein: the laser lens is a rectangular laser lens with two pairs of adjacent light-transmitting surfaces in the X-axis and Y-axis directions perpendicular to each other; the size ratio is usually length × width × height: 10 × 5 × 1, in mm, and in actual design and use, the device size does not limit the ratio. For the length and width dimensions, the principle of limiting the length and width dimensions is "sufficient for the light path to be deflected from the incident surface to the exit surface (optical path)". For the thickness dimension, the restriction condition only needs to meet the spot size, and the thickness can be designed according to different spot sizes.

[0027] Laser lens materials are optical glass materials, commonly used materials in the industry such as SiO2, Ti2O5, TiO2, Si3N4, etc.

[0028] This embodiment utilizes the property that light will bend under different refractive indices. For example, a self-focusing lens is a cylindrical optical lens with a refractive index distribution that gradually changes along the radial direction. The refractive index change curve of the self-focusing lens is symmetrical along the radial (x-axis) center, and the other axial refractive indices of the self-focusing lens remain unchanged. The design goal of the self-focusing lens is to make the light smoothly and continuously focused inside the self-focusing lens after the parallel light beam is incident. Its working mechanism is: the distribution of the refractive index of the self-focusing lens material gradually decreases radially from the center to the edge, which can cause the light transmitted along the axial direction to produce continuous refraction, thereby achieving smooth and continuous convergence of the emitted light to one point. In other words, when the light is transmitted in a fixed medium, for the vertical direction along the direction of light propagation, the light will deflect in the direction of the large refractive index. If the refractive index in this direction is uniform in all directions, the light will not deflect. As this embodiment can be understood as changing the cylinder into a rectangular body based on the design process of the self-focusing lens, the refractive index along the radial direction is variable. However, in order to achieve beam combining, the laser incident from the transmission surface on one side of the Y axis is gradually deflected under the action of the gradient refractive index, and a 90-degree bend is formed when the laser deflection reaches the transmission surface 102 on the other side of the X axis. Only in this state can beam combining be achieved, otherwise beam combining cannot be achieved.

[0029] In this embodiment: as a rectangular laser lens 1, when the gradient refractive index is determined and the position of the laser incident point in the X-axis direction is determined, the X-axis length and the Y-axis length of the laser lens are the lengths that ensure that the laser incident on the Y-axis transmission surface is gradually deflected under the action of the gradient refractive index, and when the laser deflects and reaches the other end transmission surface with a high X-axis refractive index, it forms a 90-degree curved straight line for emission.

[0030] In order to expand the application, more than one laser source is combined in one laser lens: therefore, there are two laser sources, and the two laser sources are arranged at the opposite transmission surfaces at both ends of the Y axis of the laser lens. In addition, when the laser deflects and reaches the other end transmission surface with a high refractive index on the X axis, the emission point of the laser beam is formed by a 90-degree curved straight line, which is the center point of the transmission surface at both ends of the X axis of the laser lens.

[0031] To improve the transmittance: the four light-transmitting surfaces of the laser lens are coated with high-transmittance films, which can improve the transmittance. In actual design and use, it is necessary to increase the optical power and reduce the loss in principle, so it is necessary to coat a high-transmittance film (also known as "anti-reflection film", "AR film"), in order to improve the transmittance of the film layer, generally a multi-layer film structure is used to make the transmittance of the four sides greater than 99.5%.

[0032] In order to improve the laser quality of the laser source: a fast-axis collimator 4 and a slow-axis collimator 5 are arranged in series between the laser source and the laser lens by adjusting the positioning bracket, with the fast-axis collimator 4 in front and the slow-axis collimator 5 in the back. The fast-axis collimator 4 and the slow-axis collimator 5 are used to improve the quality of laser emitted by the laser source, and adjust the deflection and bending of the laser incident in the Y-axis direction to 90 degrees to combine with the laser passing through the X-axis.

[0033] The laser source in the embodiment may be lasers generated by different laser generators. As a preferred solution, the laser source in this embodiment is a semiconductor laser chip.

[0034] Embodiment 2:

[0035] A beam combining method for a beam combining laser is based on the beam combining method of the beam combining laser device described in Example 1. Therefore, the content of Example 1 is applicable to this embodiment. The laser lens in the device is a rectangular laser lens with two pairs of adjacent light transmission surfaces perpendicular to each other in the X-axis and Y-axis directions. A fast-axis collimator and a slow-axis collimator are arranged in series between the laser source and the laser lens by adjusting the positioning bracket. The laser emitted from the laser source sequentially passes through the fast-axis collimator and the slow-axis collimator and then enters the laser lens from the Y-axis transmission surface of the laser lens. The debugging method includes:

[0036] The first step is to set a debugging laser transmitter to emit a debugging laser, and the debugging laser is injected from the X-axis low refractive index end side of the laser lenses coaxially arranged in series along the X-axis direction and passes straight through;

[0037] The second step is to turn on the laser source corresponding to each laser lens respectively, and observe it using a CCD photodetector. By adjusting the position of the laser source, the fast-axis collimator, and the slow-axis collimator corresponding to each laser lens, the laser incident from the Y-axis transmission surface is bent at a 90-degree angle when it deflects and reaches the other end transmission surface with a high refractive index on the X-axis, and then combined with the debugging laser passing through to form a combined laser and then emitted in a straight line;

[0038] The third step is to fix the laser source, fast-axis collimator and slow-axis collimator at the determined position, remove the debugging laser transmitter, and complete the beam combining debugging.

[0039] In the embodiment: there are two laser sources, and the two laser sources are arranged corresponding to the transmission surfaces on both sides of the Y-axis of the laser lens. When the laser is deflected and reaches the other end transmission surface with a high refractive index on the X-axis, it forms a 90-degree curved straight line and the emission point is the center point of the transmission surface at both ends of the X-axis of the laser lens.

[0040] The above-mentioned embodiment of a beam combining laser device and a beam combining method thereof changes the traditional method of stacking beams by using a refracting mirror to achieve a 90-degree turn of the laser. Since the beam combining means of the traditional method all have a "step" design, that is, there is a spacing in the direction of beam stacking, which means that stacking more beams (for the purpose of obtaining higher power) will deteriorate the beam quality. However, the device and method of this embodiment use a uniaxial gradient refractive index laser lens. Under the premise of achieving superimposed beams (higher power), the beam quality will not deteriorate. In theory, an unlimited number of beams can be superimposed to obtain a laser beam with higher energy density.

Claims

1. A beam combining laser device, comprising a plurality of laser lenses and laser sources arranged in series, wherein at least one laser source is provided for each laser lens, characterized in that: The laser lens has two pairs of light-transmitting surfaces, and the two pairs, four light-transmitting surfaces are respectively arranged opposite to each other in the Y-axis and X-axis directions of the laser lens, the height direction of the light-transmitting surface is the Z-axis direction of the laser lens, and multiple laser lenses are coaxially arranged in series along the X-axis direction. The laser emitted by the laser source is perpendicular to the X-axis of the laser lens and is injected from the transmission surface at one end of the Y-axis of the laser lens. The refractive index of the laser lens in the X-axis direction is a gradual refractive index, and the refractive index in the Y-axis and Z-axis directions is constant. The gradual refractive index is a gradual refractive index that gradually changes from low to high from the transmission surface at one end of the X-axis of the laser lens to the transmission surface at the other end. The laser of the laser source is incident from the Y-axis transmission surface at one end side of the X-axis, i.e., the low refractive index end side, of the laser lens. Under the action of the X-axis gradient refractive index, the incident laser is gradually deflected toward the other end side of the X-axis, i.e., the high refractive index end side. When the laser deflects and reaches the other end transmission surface with a high refractive index of the X-axis, it is emitted in a straight line with a 90-degree bend. The constant refractive index of the Y-axis causes the laser incident from the end transmission surface with a low refractive index of the X-axis to penetrate the laser lens in a straight line. The laser deflected to form a 90-degree bend in the laser lens connected in series after the starting end laser lens is emitted in a straight line after being combined with the laser emitted in a straight line from the previous adjacent laser lens to form a combined laser. When the gradient refractive index is determined and the position of the laser incident point in the X-axis direction is determined, the X-axis length and Y-axis length of the laser lens are lengths that ensure that the laser incident on the Y-axis transmission surface is gradually deflected under the action of the gradient refractive index, and when the laser deflects and reaches the other end transmission surface with a high X-axis refractive index, it forms a 90-degree curved straight line and is emitted.

2. The beam combining laser device according to claim 1, characterized in that: The laser lens is a rectangular laser lens with two pairs of adjacent light-transmitting surfaces in the X-axis and Y-axis directions being perpendicular to each other.

3. The beam combining laser device according to claim 1, characterized in that: Each of the laser lenses has two laser sources, and the two laser sources are arranged corresponding to the transmission surface at two ends of the Y axis of the laser lens.

4. The beam combining laser device according to claim 1, characterized in that: When the laser deflects and reaches the other end transmission surface with a high refractive index on the X-axis, the emission point that forms a 90-degree curved straight line is the center point of the transmission surfaces on both ends of the X-axis of the laser lens.

5. The beam combining laser device according to claim 1, characterized in that: The four light-transmitting surfaces of the laser lens are respectively coated with high-transmittance films.

6. The beam combining laser device according to claim 1, characterized in that: A fast-axis collimator and a slow-axis collimator are arranged in series between the laser source and the laser lens by adjusting the positioning bracket, with the fast-axis collimator being in front and the slow-axis collimator being in the back.

7. The beam combining laser device according to any one of the preceding claims, characterized in that: The laser source is a semiconductor laser chip.

8. A laser beam combining method, comprising the laser beam combining device according to claim 1, characterized in that: The laser lens is a rectangular laser lens with two pairs of adjacent light-transmitting surfaces perpendicular to each other in the X-axis and Y-axis directions. A fast-axis collimator and a slow-axis collimator are arranged in series between the laser source and the laser lens by adjusting the positioning bracket. The laser emitted from the laser source passes through the fast-axis collimator and the slow-axis collimator in sequence and then enters the laser lens from the Y-axis transmission surface of the laser lens. The beam combining method includes: The first step is to set a debugging laser transmitter to emit a debugging laser, and the debugging laser is injected from the X-axis low refractive index end side of the laser lenses coaxially arranged in series along the X-axis direction and passes straight through; The second step is to turn on the laser source corresponding to each laser lens respectively, and observe it using a CCD photodetector. By adjusting the position of the laser source, the fast-axis collimator, and the slow-axis collimator corresponding to each laser lens, the laser incident from the Y-axis transmission surface is bent at a 90-degree angle when it deflects and reaches the other end transmission surface with a high refractive index on the X-axis, and then combined with the debugging laser passing through to form a combined laser and then emitted in a straight line; The third step is to fix the laser source, fast-axis collimator and slow-axis collimator at the determined position, remove the debugging laser transmitter, and complete the beam combining.

9. The beam combining method according to claim 8, characterized in that: Each laser lens has two laser sources, and the two laser sources are arranged corresponding to the transmission surfaces on both sides of the Y-axis of the laser lens. When the laser is deflected and reaches the other end transmission surface with a high refractive index on the X-axis, it forms a 90-degree curved straight line and the emission point is the center point of the transmission surfaces at both ends of the X-axis of the laser lens.

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