Beam combining laser device and beam combining method therefor

Abstract

A beam combining laser device and a beam combining method therefor. The beam combining laser device comprises a plurality of laser lenses (1) which are coaxially arranged in series, and laser sources (2); each laser lens (1) has two pairs of light-transmitting surfaces, the two pairs, i.e., four light-transmitting surfaces being respectively arranged opposite to each other in an X-axis direction and a Y-axis direction; laser emitted from the laser sources (2) enters the light-transmitting surfaces of the laser lenses (1) along the Y axis, the refractive indexes of the laser lenses (1) in the X-axis direction being gradient refractive indexes, and the refractive indexes in the Y-axis direction being unchanged; the gradient refractive indexes are gradient refractive indexes gradually changing from low to high from the light-transmitting surface at one end to the light-transmitting surface at the other end of each laser lens (1) along the X axis; laser entering from the light-transmitting surfaces at one side along the Y axis is gradually deflected under the action of the gradient refractive indexes, and then bends at 90 degrees to be emitted out in a straight line when the deflected laser reaches the light-transmitting surfaces at the other side along the X axis; laser which is deflected to bend at 90 degrees in the laser lenses (1) connected in series behind a starting end laser lens (1) is combined with laser emitted out in a straight line from the previous adjacent laser lenses (1), so as to form a combined laser to be emitted out in a straight line.

Description

A beam combining laser device and its beam combining method Technical Field

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

[0002] To achieve high laser power, besides using high-power laser source devices, laser beam combining can also be employed. This method combines the lasers emitted from multiple low-power laser sources to form a high-power laser beam, which is currently the most common approach for obtaining high-power beams. However, existing beam combining techniques all have a "stepped" design, meaning there is a gap in the beam stacking direction, with vertical step spacing between the light sources. If this step spacing is eliminated, the high-reflectivity coating on the reflector surfaces will cause "reflector shading" after the light is deflected 90° by other reflectors, significantly reducing the beam combining effect and preventing complete beam combining. Even without considering reflector shading, when the light sources are arranged in a front-to-back configuration, the front light source will still block the rear light source. This limitation essentially stems from the fact that optical devices always have physical components, and physical components will always block light. This means that stacking more beams (to obtain higher power) will degrade the beam quality.

[0003] To further elaborate, in fiber coupling, the more beams stacked, the larger the fiber input NA and output NA. In other words, the larger the divergence angle of the output beam, the faster the energy density decreases during transmission (similar to beam quality difference, also known in the industry as "brightness" difference). Simultaneously, due to the fiber NA limitation, this greatly restricts the number of stacked beams, limiting the total power and power density of the semiconductor laser. This is the design bottleneck of semiconductor lasers (also known as "pump sources" or "fiber-coupled semiconductor lasers"). Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a beam combining laser device and its beam combining method, which employs a uniaxial gradient refractive index laser lens. Under the premise of achieving superimposed beams (higher power), the system beam quality does not deteriorate. Theoretically, an infinite number of beams can be superimposed, thereby obtaining a laser beam with higher energy density.

[0005] To achieve the above objectives, the present invention provides a laser beam combining device comprising multiple laser lenses and laser sources arranged in series, wherein each laser lens corresponds to at least one laser source, wherein: each laser lens has two pairs of transparent surfaces, the two pairs, or four transparent surfaces, are respectively arranged opposite each other along the mutually perpendicular Y-axis and X-axis directions of the laser lens, the height direction of the transparent surfaces is the Z-axis direction of the laser lens, the multiple laser lenses are coaxially connected in series along the X-axis direction, the laser emitted from the laser source enters from the transmission surface at one end of the laser lens along the Y-axis, the refractive index of the laser lens along the X-axis is a graded refractive index, while the refractive indices along the Y-axis and Z-axis are constant, the graded refractive index being derived from the X-axis of the laser lens. The laser source has a gradually increasing refractive index from one end of the transmission surface to the other. The laser light from the laser source enters the transmission surface at the Y-axis end of the laser lens from the low refractive index end of the X-axis. Under the action of the gradually increasing refractive index on the X-axis, the laser light entering gradually deflects towards the high refractive index end of the X-axis. When the laser light deflects to the transmission surface at the high refractive index end of the X-axis, it exits in a straight line. The constant refractive index on the Y-axis causes the laser light entering from the transmission surface at the low refractive index end of the X-axis to penetrate the laser lens in a straight line. Among them, the laser light deflected in the laser lens connected in series after the initial laser lens is combined with the laser light that exits in a straight line from the previous adjacent laser lens to form a combined laser light and then exits in a straight line.

[0006] A further aspect of the solution is that the laser from the laser source is perpendicular to the X-axis of the laser lens at the low-refractive-index side of the X-axis and enters from the Y-axis transmission surface. When the laser deflects and reaches the transmission surface at the high-refractive-index side of the X-axis, it forms a 90-degree angled curved straight line and exits.

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

[0008] The solution is further defined as follows: given the determined gradient refractive index and the determined position of the laser injection point in the X-axis direction, the length of the laser lens along the X-axis and the length along the Y-axis are such that the laser light entering 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 light deflects to the transmission surface at the other end with a higher X-axis refractive index, it exits in a straight line at a 90-degree angle to the Y-axis.

[0009] A further aspect of the solution is that each laser lens has two laser sources, which are positioned opposite each other on the transmission surface at both ends of the laser lens along the Y-axis.

[0010] A further aspect of the solution is that when the laser deflects to the other end of the transmission surface with a higher refractive index on the X-axis, the emission point that forms a 90-degree angled curved straight line is the center point of the transmission surfaces at both ends of the X-axis of the laser lens.

[0011] A further aspect of the solution is that the four light-transmitting surfaces of the laser lens are each coated with a high-transmittance film.

[0012] A further aspect of the solution is that a fast-axis collimating lens and a slow-axis collimating lens are connected in series between the laser source and the laser lens via an adjustable positioning bracket, with the fast-axis collimating lens in front and the slow-axis collimating lens behind.

[0013] The solution further states that the laser source is a semiconductor laser chip, a fiber laser, a solid-state laser, or a gas laser.

[0014] A method for combining laser beams, comprising the laser combining device, wherein: the laser lens is a rectangular laser lens with two pairs of adjacent transparent surfaces perpendicular to each other in the X-axis and Y-axis directions; a fast-axis collimating lens and a slow-axis collimating lens are connected in series between the laser source and the laser lens via an adjustment positioning bracket; the laser emitted from the laser source passes sequentially through the fast-axis collimating lens and the slow-axis collimating lens and then enters the laser lens from the Y-axis transmission surface; the beam combining method comprises: Step 1, setting up a test laser emitter to emit a test laser; the test laser enters from the low-refractive-index side of the laser lenses arranged coaxially in series along the X-axis direction and passes through in a straight line; Step 2, turning on the laser source corresponding to each laser lens respectively; observing with a CCD photodetector; by adjusting the position of the laser source corresponding to each laser lens, and the positions of the fast-axis collimating lens and the slow-axis collimating lens, the laser entering from the Y-axis transmission surface is deflected and, when reaching the transmission surface with the high refractive index on the X-axis, combines with the passing test laser to form a combined laser beam, which then exits in a straight line. The third step is to fix the laser source, fast-axis collimating lens, and slow-axis collimating lens in their designated positions, remove and adjust the laser emitter, and complete the beam combining.

[0015] A further aspect of the solution is that each laser lens has two laser sources, which are arranged opposite to the transmission surfaces on both sides of the laser lens along the Y-axis. When the laser deflects and reaches the transmission surface at the other end with a higher refractive index along the X-axis, the point at which it exits in a straight line is the center point of the transmission surfaces at both ends of the laser lens along the X-axis.

[0016] The beneficial effects of this invention are: by employing a uniaxial graded-index laser lens, the beam quality remains unchanged while achieving superimposed beams (higher power). Theoretically, an infinite number of beams can be superimposed, thereby obtaining a laser beam with higher energy density. In practical engineering applications, due to limitations in material thermal stability and coating damage threshold, existing engineering capabilities cannot achieve the effect of infinite superposition. Even so, this solution still overcomes existing design bottlenecks.

[0017] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. Attached Figure Description

[0018] Figure 1 is a planar schematic diagram of the structure of the present invention; Figure 2 is an axial schematic diagram of the structure of the present invention; Figure 3 is a schematic diagram of the refractive index variation curve along the X-axis; Figure 4 is a schematic diagram of the refractive index variation curves along the Y-axis and Z-axis. Detailed Implementation

[0019] Example 1: A laser beam combining device, as shown in Figures 1, 2, 3, and 4, includes multiple laser lenses 1 and laser sources 2 arranged in series. These laser lenses 1 and laser sources 2 are positioned on a support frame (not shown in the figures). The support frame varies depending on the intended use. Each laser lens 1 corresponds to at least one laser source 2. The laser lens is a three-dimensional lens with length, width, and height. It has two pairs of light-transmitting surfaces, and the two pairs, or four light-transmitting surfaces, are respectively arranged opposite each other along the mutually perpendicular X-axis (length) and Y-axis (width) directions of the laser lens. The height direction of the light-transmitting surfaces is along the Z-axis of the laser lens. As shown in Figures 1 and 2, multiple laser lenses 1 are arranged coaxially in series along the X-axis (length) direction. Laser 201 emitted from laser source 2 enters the transmission surface 101 at one end of the laser lens along the Y-axis. The refractive index of the laser lens along the X-axis is a graded refractive index, while the refractive indices along the Y-axis and Z-axis (perpendicular to the plane of the paper in Figure 1) remain constant. The graded refractive index is a gradually increasing refractive index from one end of the X-axis to the other. The laser 201 from the laser source enters the transmission surface 101 at one end of the laser lens along the Y-axis, i.e., the side with the lower refractive index. An optimal configuration is to enter the laser lens at one end of the X-axis perpendicular to the X-axis and from the Y-axis... Laser light incident on the X-axis transmission surface gradually deflects towards the other end of the X-axis, i.e., the side with the higher refractive index, under the influence of the graded refractive index on the X-axis. It exits in a straight line when it reaches the transmission surface 102 on the other side of the X-axis with the higher refractive index. The determination of the graded refractive index of the laser lens must satisfy the condition that laser light incident on one side of the Y-axis transmission surface gradually deflects towards the other end of the X-axis with the higher refractive index under the influence of the graded refractive index, and when the laser light deflects to the transmission surface 102 on the other side of the X-axis with the higher refractive index, it forms a curved straight line at different angles, for example, a 90-degree curved straight line. That is, laser light incident perpendicular to the X-axis direction of the laser lens deflects to the transmission surface 102 on the other side of the X-axis when it reaches this angle. A 90-degree bend is formed, and the refractive index remains constant along the Y-axis (and Z-axis (along the plane of the paper)). This causes the laser beam entering from the transmission surface at the end with the lower refractive index along the X-axis to pass through the laser lens in a straight line. Specifically, the laser beam in the laser lens connected in series after the initial laser lens, for example, a laser beam deflected to form a 90-degree bend, passes through the adjacent laser lens and is combined to form a combined laser beam 3 before exiting in a straight line. The laser lens is a rectangular laser lens consisting of two pairs of adjacent, perpendicularly spaced transmission surfaces along the X and Y axes. The typical size ratio is length × width × height: 10 × 5 × 1 mm. However, in actual design and use, the device size is not limited by this ratio. For the length and width dimensions, the principle for limiting these dimensions is that they should be sufficient to allow the light path to be deflected from the incident surface to the exit surface (optical path length). For the thickness dimension, the only constraint is that the spot size must be met; the thickness can be designed according to different spot sizes.

[0020] The laser lens material is optical glass, with commonly used materials in the industry including SiO2, Ti2O5, TiO2, and Si3N4. This embodiment utilizes the property that light bends at different refractive indices. For example, a self-focusing lens is a cylindrical optical lens with a radially gradually changing refractive index distribution. The refractive index change curve of a self-focusing lens is symmetrical along the radial (x-axis), while the refractive index remains constant along other axes. The design goal of a self-focusing lens is to ensure that after a parallel beam is incident, the light is smoothly and continuously focused inside the lens. Its working mechanism is that the refractive index distribution of the self-focusing lens material gradually decreases radially from the center to the edge, enabling continuous refraction of light propagating along the axial direction, thus achieving smooth and continuous convergence of the outgoing light to a single point. In other words, when light propagates in a fixed medium, in the direction perpendicular to the direction of light propagation, the light will deflect towards the direction with a higher refractive index. If the refractive index is uniform in this direction, the light will not deflect. In this embodiment, it can be understood that the design and manufacturing process of a self-focusing lens is based on changing the cylinder to a rectangle, with the refractive index varying radially. However, in order to achieve beam combining, the laser light 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 light deflects to the transmission surface 102 on the other side of the X-axis, it forms a 90-degree angle bend. Only under this state can beam combining be achieved; otherwise, beam combining cannot be achieved.

[0021] In this embodiment: As a rectangular laser lens 1, under the condition that the gradient refractive index is determined and the position of the laser injection point in the X-axis direction is determined, the length of the X-axis and the length of the Y-axis of the laser lens are the lengths that ensure that the laser injected into the Y-axis transmission surface is gradually deflected under the action of the gradient refractive index, and when the laser deflects to the other end of the transmission surface with a higher X-axis refractive index, it is emitted in a straight line at a 90-degree angle with the Y-axis.

[0022] To expand applications, laser beam combining of more than one laser source can be achieved within a single laser lens: therefore, each laser lens has two laser sources, positioned opposite each other at the two ends of the lens's Y-axis transmission surface. Furthermore, the point where the laser beam, deflected and reaching the transmission surface with the higher refractive index on the X-axis, exits as a 90-degree curved straight line is the center point of the transmission surfaces at both ends of the laser lens's X-axis.

[0023] To improve light transmittance, the four light-transmitting surfaces of the laser lens are each coated with a high-transmittance film, which enhances transmittance. In practical design and use, it is generally necessary to increase optical power and reduce losses, thus requiring the coating of a high-transmittance film (also known as an anti-reflection film or AR film). To further improve the transmittance of the film layer, a multi-layer film structure is typically used, ensuring that the transmittance of all four sides is greater than 99.5%.

[0024] To improve the laser quality of the laser source, a fast-axis collimating lens 4 and a slow-axis collimating lens 5 are connected in series between the laser source and the laser lens via an adjustable positioning bracket. The fast-axis collimating lens 4 is in front and the slow-axis collimating lens 5 is behind. The fast-axis collimating lens 4 and the slow-axis collimating lens 5 are used to improve the quality of the laser emitted from the laser source and to adjust the deflection and bending of the laser beam incident in the Y-axis direction to 90 degrees so that it merges with the laser beam passing through the X-axis.

[0025] The laser source in the embodiments can be laser generated by different laser generators. As a preferred embodiment, the laser source in this embodiment is a semiconductor laser chip, a fiber laser, a solid-state laser, or a gas laser.

[0026] Example 2: A method for combining laser beams, which is based on the laser beam combining device described in Example 1. Therefore, the content of Example 1 is applicable to this example. The laser lens in the device is a rectangular laser lens with two pairs of adjacent transparent surfaces perpendicular to each other in the X-axis and Y-axis directions. A fast-axis collimating lens and a slow-axis collimating lens are connected in series between the laser source and the laser lens through an adjustment positioning bracket. The laser emitted from the laser source passes sequentially through the fast-axis collimating lens and the slow-axis collimating lens and then enters the laser lens from the Y-axis transmission surface of the laser lens. The debugging method includes: First, setting up a debugging laser emitter to emit debugging laser. The debugging laser enters from the low-refractive-index side of the laser lenses arranged coaxially in series along the X-axis direction and passes through them in a straight line. The second step is to turn on the laser source corresponding to each laser lens and observe using a CCD photodetector. By adjusting the position of the laser source, fast-axis collimator, and slow-axis collimator corresponding to each laser lens, the laser beam entering from the Y-axis transmission surface is deflected and, upon reaching the X-axis transmission surface with a higher refractive index, is combined with the passing test laser to form a combined laser beam that is then emitted in a straight line. For example, the laser beam entering perpendicularly from the Y-axis transmission surface is deflected and, upon reaching the X-axis transmission surface with a higher refractive index, forms a 90-degree bend and is combined with the passing test laser beam to form a combined laser beam that is then emitted in a straight line. The third step is to fix the laser source, fast-axis collimator, and slow-axis collimator in their determined positions, remove the test laser emitter, and complete the beam combining adjustment.

[0027] In the embodiment: each laser lens has two laser sources, and the two laser sources are arranged opposite to the transmission surfaces on both sides of the laser lens along the Y-axis. When the laser deflects and reaches the transmission surface at the other end with a higher refractive index on the X-axis, the emission point of the straight line (e.g., forming a 90-degree curved straight line) is the center point of the transmission surfaces at both ends of the laser lens along the X-axis.

[0028] The aforementioned embodiment of a laser beam combining device and its beam combining method changes the traditional method of achieving 90-degree laser beam redirection via a refracting mirror. Traditional beam combining methods all have a "stepped" design, meaning there is a gap in the beam stacking direction. This implies that stacking more beams (to obtain higher power) will degrade beam quality. However, the device and method in this embodiment use a single-axis graded-index laser lens. While achieving superimposed beams (higher power), the beam quality does not degrade. Theoretically, an infinite number of beams can be superimposed, thereby obtaining 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 with each other, one laser lens corresponding to at least one laser source, characterized in that, The laser lens has two pairs of light transmission surfaces, and the two pairs of four light transmission surfaces are oppositely arranged in the directions of the mutually perpendicular Y-axis and X-axis of the laser lens, the height direction of the light transmission surface is the Z-axis direction of the laser lens, a plurality of laser lenses are coaxially arranged in series along the X-axis direction, the laser emitted by the laser source is incident 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 indices in the Y-axis direction and the Z-axis direction are constant, the gradient refractive index is a gradient refractive index gradually changing 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 transmission surface in the Y-axis at the low end side of the X-axis refractive index of the laser lens, and the laser incident under the action of the X-axis gradient refractive index gradually deflects to the high end side of the X-axis refractive index, and the laser is linearly emitted when the laser deflection reaches the transmission surface at the high end of the X-axis refractive index, and the constant refractive index in the Y-axis direction causes the laser incident from the transmission surface at the low end of the X-axis refractive index to linearly penetrate the laser lens, wherein: the deflected laser in the laser lens connected in series after the starting end laser lens is linearly emitted after the laser is combined to form combined laser with the linearly emitted laser of the previous adjacent laser lens.

2. The beam combining laser device of claim 1, wherein, The laser emitted by the laser source is incident from the transmission surface in the Y-axis at the low end side of the X-axis refractive index of the laser lens perpendicularly to the X-axis of the laser lens, and the laser is linearly emitted at a 90-degree angle when the laser deflection reaches the transmission surface at the other end of the high X-axis refractive index.

3. The beam combining laser device of claim 1, wherein, The laser lens is a rectangular body laser lens with two pairs of adjacent light transmission surfaces in the X-axis and Y-axis directions being perpendicular to each other.

4. The beam combining laser device of claim 1, wherein, In the state that the gradient refractive index is determined and the position of the laser incident point in the X-axis direction is determined, the length of the X-axis and the length of the Y-axis of the laser lens are lengths that ensure that the laser incident from the transmission surface in the Y-axis gradually deflects under the action of the gradient refractive index and is linearly emitted at a 90-degree angle with the Y-axis when the laser deflection reaches the transmission surface at the other end of the high X-axis refractive index.

5. The beam combining laser device of claim 1, wherein, Each of the laser lenses has two laser sources, and the two laser sources are arranged opposite to the transmission surfaces at the two ends of the Y-axis of the corresponding laser lens.

6. The beam combining laser device of claim 1, wherein, The emission point at which the laser is linearly emitted at a 90-degree angle when the laser deflection reaches the transmission surface at the other end of the high X-axis refractive index is the center point of the transmission surfaces at the two ends of the X-axis of the laser lens.

7. The beam combining laser device of claim 1, wherein, The four light transmission surfaces of the laser lens are respectively coated with a high-transmission film.

8. The beam combining laser device of claim 1, wherein, A fast-axis collimating mirror and a slow-axis collimating mirror are connected in series between the laser source and the laser lens through an adjusting positioning support, and the fast-axis collimating mirror is in front and the slow-axis collimating mirror is behind.

9. The beam combining laser device of any preceding claim, wherein, The laser source is a semiconductor laser chip, a fiber laser, a solid-state laser, or a gas laser.

10. A method of beam combining a plurality of laser beams, comprising the beam combining laser device of claim 1, wherein, The laser lens is a rectangular body laser lens with two pairs of adjacent light transmission surfaces in the X-axis and Y-axis directions being perpendicular to each other, and a fast-axis collimating mirror and a slow-axis collimating mirror are connected in series between the laser source and the laser lens through an adjusting positioning support, and the laser emitted from the laser source enters the laser lens from the transmission surface in the Y-axis of the laser lens after sequentially passing through the fast-axis collimating mirror and the slow-axis collimating mirror, and the combining method comprises: Step 1: A debugging laser emitter is arranged to emit debugging laser, and the debugging laser is incident from the low end side of the X-axis refractive index of the laser lens coaxially arranged in series along the X-axis direction and linearly penetrates. Second step, open each laser lens corresponding laser source, using CCD light detector observation, by adjusting the position of each laser lens corresponding laser source, fast axis collimating mirror and slow axis collimating mirror position, from the Y axis transmission surface into the laser when deflected to reach the other end of the X axis refractive index high transmission surface with the through debugging laser beam forming beam laser after straight line out; Third step, the laser source, fast axis collimating mirror and slow axis collimating mirror fixed position, remove the debugging laser emitter, complete the beam.

11. The beam combining method of claim 10, wherein, Each of the laser lens has two laser sources, two laser sources corresponding to the laser lens Y axis both sides of the relative transmission surface is provided, the laser deflection to reach the other end of the X axis refractive index high transmission surface when straight line out of the exit point is the center point of the laser lens X axis both ends of the transmission surface.

Images