A disk gain medium structure laser assembly

Abstract

The application discloses a laser assembly with disc gain medium structure, which comprises fiber-coupled output semiconductor laser, lens, conical mirror, lens, circular disc, output coupling mirror arranged in sequence, and a circle of taper surface is arranged on the side of the circular disc; the pump light emitted by the fiber-coupled output semiconductor laser is collimated by the lens, is transformed into annular light beam by the conical mirror, is focused by the lens, annular fine light beam is generated, is incident on the bottom surface of the circular disc, is reflected by the taper surface of the side of the circular disc, and is transmitted along the radius of the circular disc to the center, so that the pump absorption is realized; the bottom surface of the circular disc is coated with laser high reflection film, the high reflection film and the output coupling mirror jointly form a pair of cavity mirrors, and the laser is oscillated under the pump action and is outputted. The fiber-coupled output laser is transformed into annular laser by simple conical mirror transformation technology, is folded by nearly 90 degrees, and is pumped along the side of the circular disc, so that the laser assembly has the advantages of simple pump structure, convenient debugging and maintenance and the like.

Description

Technical Field

[0001] This invention relates to a solid-state laser, and more particularly to a laser assembly with a disk gain medium structure. Background Technology

[0002] The main configurations of solid-state lasers include rod lasers, slab lasers, disk lasers, and fiber lasers. Among them, disk lasers have a large gain medium cross-section / thickness ratio, can maintain excellent beam quality under high power loads, and can withstand both high peak power and high average power. They have been widely used in the fields of high-brightness continuous lasers and high peak power ultrashort pulse lasers.

[0003] Disk lasers originated in the 1970s and, thanks to their large aperture and large heat dissipation area, have the potential for high energy output.

[0004] Currently, there are two main technical solutions for disk lasers: one is multi-pass pumped disk laser technology, and the other is side-pumped disk laser technology.

[0005] Multi-pump disk lasers achieve high-efficiency pumping by using a complex pump optical path design to allow the pump light to pass through the pump gain medium multiple times. Due to the complexity of the pump structure, precise assembly and adjustment techniques are required. This complex pump structure also affects the laser's robustness, resulting in generally poor resistance to shock and vibration.

[0006] In the prior art, side-pumped disk laser technology includes:

[0007] In 2002, J. Vetrovec of Boeing proposed two compact active mirror laser structures that could achieve efficient pumping using a simple structure by side-pumping a disk with a thickness of 1–3 mm. In 2012, the team developed side-pumped disks of different materials (Yb:Glass, Yb:C-YAG, and composite ceramic Sm / Nd:YAG), conducted performance tests, and concluded that this structure was suitable for high-power laser systems with kilowatts or ~J-level high-energy pulses and diffraction-limited beam quality.

[0008] The aforementioned work on side-pumped disk lasers has provided new insights for engineers regarding the simplification of pump optical paths and suppression of ASE (associated laser-induced degradation). However, these side-pumped lasers also have significant drawbacks. First, the limited pump structure restricts the number of laser diodes that can be arranged on the side, thus limiting the pump power. Second, the arrangement of the pump diodes requires independent design, resulting in complex packaging and difficult maintenance. These shortcomings limit the application and development of side-pumped disks, especially in industrial fields with stringent cost and maintenance requirements.

[0009] This invention addresses the problems of complex pumping structures, difficult assembly and adjustment, and high maintenance costs in traditional multi-pump disk lasers, as well as the limited number of diodes and limited pump power in side-pump disk lasers. Summary of the Invention

[0010] The purpose of this invention is to provide a laser assembly with a disk gain medium structure to solve the aforementioned technical problems in the prior art.

[0011] The objective of this invention is achieved through the following technical solution:

[0012] The laser assembly with a disk gain dielectric structure of the present invention constitutes a laser oscillator or a laser amplifier:

[0013] The laser oscillator includes a fiber-coupled output semiconductor laser 1, a lens 3, a conical mirror 4, a lens 5, a circular disk 7, and an output coupling mirror 8 arranged in sequence. The side of the circular disk 7 is provided with a conical surface.

[0014] The pump light 2 emitted by the fiber-coupled output semiconductor laser 1 is collimated by lens 3, transformed into a ring beam by conical mirror 4, and focused by lens 5 to generate a ring-shaped thin beam. It is incident on the bottom surface of the circular disk 7, reflected by the side conical surface of the circular disk 7, and then propagated towards the center along the radius of the circular disk 7 to achieve absorption pumping. The laser amplifier includes fiber-coupled output semiconductor laser 1, lens 3, conical mirror 4, lens 5, and circular disk 7. The side of the circular disk 7 is provided with a ring of conical surfaces.

[0015] Laser 12 is injected into the laser amplifier. Laser 12 forms a certain angle with the lower surface of the circular disk 7. Laser 12 is amplified after being reflected by the lower surface of the disk.

[0016] Compared with the prior art, the laser assembly with a disk gain medium structure provided by the present invention uses a simple conical mirror transformation technique to transform the fiber-coupled output laser into a ring laser, which is then pumped along the side of the circular disk after being folded at nearly 90°. It has the advantages of simple pumping structure and convenient debugging and maintenance. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the side-pumped circular disk laser assembly structure in an embodiment of the present invention;

[0018] Figure 2 These are various structures of the circular disc in the embodiments of the present invention;

[0019] Figure 3a , Figure 3b These are two cavity structures of the circular disc in the embodiments of the present invention;

[0020] Figure 4 This is the structure of the laser amplifier in an embodiment of the present invention.

[0021] In the picture:

[0022] 1: Fiber-coupled semiconductor laser; 2: Pump light; 3: Lens; 4: Conical mirror; 5: Lens; 6: Substrate; 7: Circular disk; 8: Output coupling mirror; 9: Laser; 10: Cooling medium; 11: High-reflection mirror; 12: Laser;

[0023] 21: Pump light;

[0024] 62: Transparent heat sinks such as sapphire or diamond; 63: Heat sinks made of thermally conductive materials such as tungsten copper;

[0025] 71: Yb: YAG region; 72: YAG region; 73: 1030nm laser antireflection coating; 74: Laser high reflectivity and pump light antireflection coating; 75: YAG end cap. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them, and do not constitute a limitation on the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the protection scope of the present invention.

[0027] First, the following explanations are provided for the terms that may be used in this article:

[0028] The term "and / or" means that either or both can be achieved simultaneously. For example, X and / or Y means that it includes both "X" or "Y" as well as the three cases of "X and Y".

[0029] The terms “including,” “comprising,” “containing,” “having,” or other similar semantic descriptions should be interpreted as non-exclusive inclusion. For example, “including a technical feature element (such as raw material, component, ingredient, carrier, dosage form, material, size, part, component, mechanism, device, step, process, method, reaction conditions, processing conditions, parameter, algorithm, signal, data, product or article of manufacture, etc.)” should be interpreted as including not only the expressly listed technical feature element, but also other technical feature elements that are not expressly listed and are well-known in the art.

[0030] The term "composed of" excludes any technical features not expressly listed. When used in a claim, it closes the claim to exclude all technical features other than those expressly listed, except for associated conventional impurities. If the term appears only in a clause of a claim, it limits the claim to the elements expressly listed in that clause; elements recited in other clauses are not excluded from the overall claim.

[0031] Unless otherwise explicitly specified or limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this document according to the specific circumstances.

[0032] The terms “center,” “longitudinal,” “lateral,” “length,” “width,” “thickness,” “upper,” “lower,” “front,” “back,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” “outer,” “clockwise,” and “counterclockwise” indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience and simplification of description and do not imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this document.

[0033] The contents not described in detail in the embodiments of this invention are prior art known to those skilled in the art. Where specific conditions are not specified in the embodiments of this invention, they shall be performed according to conventional conditions in the art or conditions recommended by the manufacturer. Where the manufacturers of the reagents or instruments used in the embodiments of this invention are not specified, they are all conventional products that can be purchased commercially.

[0034] The laser assembly with a disk gain dielectric structure of the present invention constitutes a laser oscillator or a laser amplifier:

[0035] The laser oscillator includes a fiber-coupled output semiconductor laser 1, a lens 3, a conical mirror 4, a lens 5, a circular disk 7, and an output coupling mirror 8 arranged in sequence. The side of the circular disk 7 is provided with a conical surface.

[0036] The pump light 2 emitted by the fiber-coupled output semiconductor laser 1 is collimated by lens 3, transformed into a ring beam by conical mirror 4, and focused by lens 5 to generate a ring-shaped thin beam. It is incident on the bottom surface of the circular disk 7, reflected by the side conical surface of the circular disk 7, and then propagated towards the center along the radius of the circular disk 7 to achieve absorption pumping. The laser amplifier includes fiber-coupled output semiconductor laser 1, lens 3, conical mirror 4, lens 5, and circular disk 7. The side of the circular disk 7 is provided with a ring of conical surfaces.

[0037] Laser 12 is injected into the laser amplifier. Laser 12 forms a certain angle with the lower surface of the circular disk 7. Laser 12 is amplified after being reflected by the lower surface of the disk.

[0038] The bottom surface of the circular disk 7 is coated with a high-reflectivity laser film. This high-reflectivity film and the output coupling mirror 8 together form a pair of cavity mirrors. The laser oscillates under the pumping action through this pair of cavity mirrors and outputs the laser 9.

[0039] The bottom surface of the circular disc 7 is provided with a substrate 6, which serves as a support or heat sink for the circular disc 7; or, the substrate 6 is not provided.

[0040] The diameter of the circular disc 7 is 5mm to 50mm.

[0041] The circular disk 7 and the substrate 6 can be any of the following structures:

[0042] 1. Without a substrate 6, the circular disk 7 has a Yb:YAG region 71 in the middle and a YAG region 72 around the periphery, which are used for laser gain and heat pump-free optical coupling, respectively. The upper surface of the circular disk 7 is coated with a 1030nm laser anti-reflection film 73, and the lower surface is coated with a laser high reflectivity and pump light anti-reflection film 74. A cooling medium 10 is provided below.

[0043] Second, based on structure one, a YAG end cap 75 is bonded on the top of the circular disk 7 to increase spontaneous emission loss and suppress ASE, and the 1030nm laser anti-reflection film 73 is deposited on the upper surface of the YAG end cap 75.

[0044] Third, based on structure one, a substrate 6 is bonded to the lower surface of the circular disc 7. The substrate 6 is a transparent heat sink 62 made of sapphire or diamond.

[0045] Fourth, based on structure one, a substrate 6 is welded to the lower surface of the circular disc 7. The substrate 6 is a heat sink 63 made of tungsten copper thermal conductive material.

[0046] The laser oscillation cavity formed by the high-reflectivity laser film on the bottom surface of the circular disk 7 and the output coupling mirror 8 includes any of the following structures:

[0047] 1. The output coupling mirror 8 is positioned directly opposite the circular disc 7, and the lower surface of the output coupling mirror 8 is perpendicular to the lower surface of the circular disc 7;

[0048] II. The cavity mirror is equipped with a high-reflection mirror 11. The output coupling mirror 8 and the high-reflection mirror 11 are respectively tilted to the circular disk 7, and the laser is at a certain angle to the lower surface of the circular disk 7.

[0049] In summary, the laser assembly with a disk gain medium structure according to the embodiments of the present invention is a novel side-pumped disk laser technology. It uses a simple conical mirror transformation technique to transform the fiber-coupled output laser into a ring laser, which is then pumped along the side of a circular disk after a near 90° fold. It has the advantages of simple pumping structure and convenient debugging and maintenance.

[0050] To more clearly demonstrate the technical solution and its effects provided by the present invention, the embodiments of the present invention will be described in detail below with reference to specific examples.

[0051] Example 1

[0052] like Figure 1 As shown:

[0053] A ring-beam radially pumped disk laser, the structure of which is as follows: Figure 1 As shown:

[0054] The fiber-coupled output semiconductor laser 1 emits a pump light 2, which is collimated by a lens 3, then transformed into a ring beam by a conical mirror 4. This ring beam is then focused by a lens 5, producing a narrow ring beam that enters the bottom surface of a circular disk 7. After reflection from the conical side surface of the disk 7, the beam propagates along the radius of the disk towards the center, achieving high-efficiency absorption pumping. The substrate 6 serves as a support or heat sink for the circular disk 7. 8 is the output coupling mirror. Typically, a high-reflectivity laser film is deposited on the bottom surface of 7. This film, together with the coupling mirror 8, forms a pair of cavity mirrors. The laser oscillates under pumping action through these cavity mirrors and is then output as laser light 9.

[0055] In this invention, the disk has a certain diameter (generally 5mm to 50mm). The pump light enters the gain medium through the side of the disk and propagates radially along the disk, exhibiting a large absorption length, enabling high-efficiency single-pass absorption pumping. By optimizing parameters such as doping concentration and diameter, or by employing nonlinear doping in the radial direction, uniform pumping can be achieved. Compared to multi-pass pumping, this method offers advantages such as simple structure and convenient assembly / adjustment. Compared to the side-pumping method described above, it eliminates the need for complex pump optics around the disk; it only requires converting the laser light from fiber-coupled semiconductor lasers of various power levels into a ring shape, which is then coupled into the disk from the side. There is virtually no concern about insufficient space around the disk to accommodate enough laser diodes. This invention, compared to the aforementioned side-pumping method, also offers advantages such as simple structure, convenient assembly / adjustment, and high pump power.

[0056] In this invention, the circular disk 7 and the substrate 6 can have various structural forms. For example... Figure 2 As shown in (a) to (d), the gain medium in the figures is Yb:YAG, the pump light is 940nm, and the output laser is 1030nm. In reality, the gain medium material is not limited to this example, but includes, but is not limited to, Nd:YAG, Tm:YAG, Ho:YAG, Ho:KYW, Yb:CALGO, Cr:ZnSe, Yb:LuScO3, and Yb:Lu2O3, which are suitable for processing into disk-shaped gain media. The pump light wavelength is changed accordingly depending on the gain medium. When the circular disk is thick enough, substrate 6 may not be necessary, and other methods can be considered. Figure 2 (a) shows a simplified scheme where the circular disk, from the center outwards, has Yb:YAG region 71 and YAG region 72, used for laser gain and heat-pump-free optical coupling, respectively. The upper surface of the circular disk crystal is coated with a 1030nm laser antireflection film 73, and the lower surface is coated with a laser high-reflection film and a pump light antireflection film 74. The composite circular disk is directly cooled by cooling medium 10. When the power is increased, this can be considered... Figure 2 Scheme (b) shown, in Figure 2 (a) A YAG end cap 75 is bonded to the top of the circular disk to increase spontaneous emission loss and suppress ASE. In this structure, a 1030nm laser antireflection film 73 is deposited on the surface of the YAG end cap 75. With further increases in power, it is possible to consider... Figure 2 As shown in scheme (c), the composite circular disc is bonded to a transparent heat sink 62, such as sapphire or diamond. Sapphire or diamond heat sinks are transparent to the pump light and have high thermal conductivity, making them excellent heat sink materials. However, this scheme requires a high-precision bonding process. Figure 2 (d) is a more easily implemented solution, which involves welding a composite circular disc onto a heat sink 63 made of thermally conductive materials such as tungsten copper to achieve efficient heat dissipation.

[0057] In this invention, the laser oscillation cavity based on the circular disk 7 can have various structural forms. Among them, two typical cavity types are as follows: Figure 3a , Figure 3b As shown. Figure 3a In the diagram, 8 represents the laser output coupling mirror. The upper surface of the circular disc crystal is coated with a laser anti-reflection film 73, and the lower surface is coated with both a laser high-reflectivity film and a pump light anti-reflection film 74. The laser high-reflectivity film serves as the high-reflectivity mirror within the cavity mirror. The laser and output coupling mirrors are perpendicular to each other. Alternatively, [further details could be considered]. Figure 3b In the illustrated scheme, 8 is the laser output coupling mirror, and 11 is the high-reflectivity mirror in the cavity mirror. The laser is reflected on the lower surface 74 of the gain circular disk. The laser is at a certain angle to the lower surface, and correspondingly, the high-reflectivity film coated on the lower surface of the laser needs to have a high reflectivity at this angle.

[0058] In this invention, the laser oscillation cavity based on the circular disk 7 can also serve as an amplifier structure. For example... Figure 4 As shown, laser 12 is injected into the laser amplifier. The laser is at a certain angle to the lower surface of the circular disk 7. The laser is amplified after being reflected by the lower surface of the disk.

[0059] The key technical feature of this invention is the ring beam pumping structure. It employs a simple conical mirror transformation technique to convert the fiber-coupled output laser into a ring laser, which is then pumped along the side of a circular disk after a near 90° deflection. Compared to multi-pass pumping disks, this structure offers advantages such as simpler pumping structure and easier debugging and maintenance. Compared to the side-pumping structure proposed by Boeing, it utilizes a mature fiber coupling module, and the pumping power is not limited by the side space. The radial pumping structure of the ring beam is the key point for protection in this patent.

[0060] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims. The information disclosed in the background section is intended only to enhance the understanding of the overall background technology of the present invention and should not be construed as an admission or implication in any way that such information constitutes prior art known to those skilled in the art.

Claims

1. A laser assembly with a disk-based gain dielectric structure, characterized in that, This component constitutes a laser oscillator or laser amplifier: The laser oscillator includes a fiber-coupled output semiconductor laser (1), a lens (3), a conical mirror (4), a lens (5), a circular disk (7), and an output coupling mirror (8) arranged in sequence. The side of the circular disk (7) is provided with a conical surface. The pump light (2) emitted by the fiber-coupled output semiconductor laser (1) is collimated by the lens (3), then transformed into a ring beam by the conical mirror (4), and focused by the lens (5) to generate a ring-shaped thin beam. It is incident on the bottom surface of the circular disk (7), and after being reflected by the side conical surface of the circular disk (7), it is transmitted along the radius of the circular disk (7) towards the center, thus realizing absorption pumping. The laser amplifier includes a fiber-coupled output semiconductor laser (1), a lens (3), a conical mirror (4), a lens (5), and a circular disk (7), wherein the side of the circular disk (7) is provided with a conical surface; A laser (12) is injected into the laser amplifier. The laser (12) forms a certain angle with the lower surface of the circular disk (7). The laser (12) is amplified after being reflected by the lower surface of the disk. The bottom surface of the circular disc (7) is coated with a high-reflectivity laser film. The high-reflectivity film and the output coupling mirror (8) together form a pair of cavity mirrors. The laser oscillates under the pumping action through this pair of cavity mirrors and outputs the laser (9).

2. The laser assembly with a disk gain dielectric structure according to claim 1, characterized in that, The bottom surface of the circular disc (7) is provided with a substrate (6), which serves as a support or heat sink for the circular disc (7); or, no substrate (6) is provided.

3. The laser assembly with a disk gain dielectric structure according to claim 2, characterized in that, The diameter of the circular disc (7) is 5mm to 50mm.

4. The laser assembly with a disk gain dielectric structure according to claim 3, characterized in that, The circular disc (7) and the substrate (6) can be any of the following structures:

1. No substrate (6) is provided. The center of the circular disk (7) is a Yb:YAG region (71) and the periphery is a YAG region (72), which are used for laser gain and heat pump-free optical coupling, respectively. The upper surface of the circular disk (7) is coated with a 1030nm laser antireflection film (73), and the lower surface is coated with a laser high reflectivity and pump light antireflection film (74). A cooling medium (10) is provided below.

2. Based on structure one, a YAG end cap (75) is bonded on the top of the circular disk (7) to increase spontaneous emission loss and suppress ASE, and the 1030nm laser anti-reflection film (73) is deposited on the upper surface of the YAG end cap (75); 3. Based on structure one, a substrate (6) is bonded to the lower surface of the circular disc (7). The substrate (6) is made of sapphire or diamond transparent heat sink (62). Fourth, based on structure one, a substrate (6) is welded to the lower surface of the circular disc (7), and the substrate (6) is a tungsten copper heat sink (63).

5. The laser assembly with a disk gain dielectric structure according to claim 4, characterized in that, The laser oscillation cavity formed by the high-reflectivity laser film on the bottom surface of the circular disk (7) and the output coupling mirror (8) includes any of the following structures:

1. The output coupling mirror (8) is set opposite to the circular disk (7), and the laser is perpendicular to the lower surface of the circular disk (7); 2. A high-reflection mirror (11) is provided in the cavity mirror. The output coupling mirror (8) and the high-reflection mirror (11) are respectively tilted to the circular disk (7). The laser is at a certain angle to the lower surface of the circular disk (7).

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