Beam actively controlled disk laser amplifier

Abstract

This application belongs to the field of laser amplification technology and provides a beam-actively controlled disk laser amplifier, comprising: a disk crystal for laser amplification; a seed light source for providing a polarized seed laser to be amplified, the seed laser having a first diameter spot at the disk crystal, and the size of the first diameter spot being dynamically adjustable; a pumping device for pumping the disk crystal, the pump light emitted by the pumping device having a second diameter spot at the disk crystal; and a spot adjustment component for dynamically adjusting the size of the first diameter spot, so that the ratio of the first diameter spot to the second diameter spot is within a preset range. This application uses a spot analysis device to monitor the diameter of the output seed amplified laser spot and uses a surface shape adjustment mirror to calibrate the spot diameter of the seed light in real time, thereby achieving a stable output spot diameter from low to high pump power and under power fluctuations, thus ensuring the stability of the output laser power and beam quality.

Description

Technical Field

[0001] This application relates to the field of laser amplifiers, and more specifically, to a beam-actively controlled disk laser amplifier. Background Technology

[0002] A disk laser multipass amplifier is a type of solid-state laser amplifier, mainly consisting of a disk-shaped gain crystal, a pump source, optical lenses, and a seed laser. The pump light generated by the pump source is injected into the disk-shaped gain crystal, causing population inversion of electrons within the crystal, placing them in an "energy storage" state. The optical lenses guide the seed laser through the disk-shaped gain crystal multiple times, continuously extracting pump energy and amplifying the seed light's power to achieve high-power or high-energy laser output.

[0003] Because the thickness of the disc-shaped gain crystal is very thin, typically 100-300 μm, the amplification of the seed light after a single pass is relatively small, requiring multiple passes to continuously extract pump energy. To ensure energy extraction efficiency, the seed light needs to be incident on the pump center position of the disc-shaped gain crystal each time. As the pump power increases, the disc-shaped gain crystal exhibits a thermal lensing effect, gradually changing from a planar surface to a convex surface. Therefore, after the seed light passes through the disc-shaped gain crystal multiple times, the spot size continuously increases, reducing energy extraction efficiency.

[0004] The existing technical solution involves first fabricating a concave gain crystal. As the pump power increases, the thermal lensing effect gradually transforms the crystal from convex to planar. Then, the seed light is passed through the gain crystal multiple times to ensure a relatively constant spot size and magnification. However, this method limits the laser's operation to a fixed pump power. Fluctuations in pump power cause changes in the seed spot diameter, severely impacting the output power and beam quality. Summary of the Invention

[0005] The purpose of this application is to provide a beam-actively controlled disk laser amplifier that can solve at least one of the aforementioned technical problems. The specific solution is as follows:

[0006] According to a specific embodiment of this application, this application proposes a beam-actively controlled disk laser amplifier, comprising:

[0007] Disc crystals are used to achieve laser amplification;

[0008] A seed light source is used to provide a polarized seed laser to be amplified, wherein the seed laser to be amplified has a first diameter spot at the disk crystal, and the size of the first diameter spot is dynamically adjustable.

[0009] A pumping device for pumping the disk crystal, wherein the pump light emitted by the pumping device has a second diameter spot at the disk crystal;

[0010] The light spot adjustment component is used to dynamically adjust the size of the first diameter light spot so that the ratio of the first diameter light spot to the second diameter light spot is within a preset range.

[0011] In some embodiments, the spot adjustment component includes:

[0012] A surface shape adjustment mirror is disposed in the laser amplification optical path, and the size of the first diameter light spot is dynamically adjusted by adjusting the surface shape of the surface shape adjustment mirror.

[0013] In some embodiments, the spot adjustment component further includes:

[0014] A spot analysis device is installed outside the laser amplification optical path. It controls the surface shape of the surface shape adjustment mirror by analyzing the spot size of the output amplified laser, so as to dynamically adjust the size of the first diameter spot.

[0015] In some embodiments, controlling the surface shape of the surface shape adjustment mirror by analyzing the spot size of the amplified laser output, so as to dynamically adjust the size of the first diameter spot, includes:

[0016] The spot analysis device measures the spot diameter of the amplified laser output and compares it with a set value. If the measured spot diameter is less than the set value, the surface shape of the surface adjustment mirror is controlled to be convex; if the measured spot diameter is greater than the set value, the surface shape of the surface adjustment mirror is controlled to be concave, until the spot diameter monitored by the spot analysis device is within the set value range.

[0017] In some embodiments, the radius of curvature of the reflective surface of the shape adjustment mirror varies from -0.2 to 0.2 m. -1 .

[0018] In some embodiments, the preset range is 0.7-0.8.

[0019] In some embodiments, the seed laser to be amplified passes through a disk crystal at least 12 times to achieve amplified output.

[0020] In some embodiments, the disk crystal material is Yb:YAG, with a doping concentration of 5% to 20%, a diameter ≥ 10 mm, and a thickness of 100 to 500 µm.

[0021] In some embodiments, it also includes:

[0022] The output mirror reflects at least 99% of the amplified laser light, while the remaining less than 0.1% of the amplified laser light passes through the output mirror and enters the spot analysis device.

[0023] In some embodiments, the pump light power of the pumping device is adjustable, and the size of the second diameter light spot is adjustable.

[0024] Compared with the prior art, the above-described solutions of this application have at least the following beneficial effects:

[0025] The active beam control disk laser amplifier provided in this application monitors the diameter of the output seed amplified laser spot using a spot analysis device and calibrates the spot diameter of the seed light in real time using a surface shape adjustment mirror, forming an active control optical path of monitoring and correction. This achieves a stable output spot diameter from low to high pump power and under power fluctuations, thereby ensuring the stability of the output laser power and beam quality. Attached Figure Description

[0026] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. In the drawings:

[0027] Figure 1 This is a schematic diagram of the structure of a disk laser amplifier with active beam control provided in an embodiment of the present invention.

[0028] Explanation of reference numerals in the attached figures:

[0029] In the diagram: 1. Seed light source; 2. Polarizing beam splitter; 3. Quarter-wave plate; 4-1. First 0-degree reflector; 4-6. Second 0-degree reflector; 4-4. Third 0-degree reflector; 4-3. Fourth 0-degree reflector; 4-2. Sixth 0-degree reflector; 4-5. Seventh 0-degree reflector; 5. Disc crystal; 6. Pumping device; 7. Surface shape adjustment mirror; 8. Fifth 0-degree reflector; 9-1. First 45-degree reflector; 9-2. Second 45-degree reflector; 10. Spot analysis device. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0031] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one" does not exclude the presence of other identical elements in the article or device that includes said element.

[0032] To suppress the thermal lensing effect of disk-shaped gain crystals, existing techniques first process the disk-shaped gain crystal as concave. As the pump power increases, the thermal lensing effect gradually transforms the crystal from convex to planar, thus ensuring a relatively constant spot size and magnification. However, this places higher demands on crystal processing technology. Furthermore, this method limits the laser's operation to a fixed pump power. If the pump power changes or fluctuates, it becomes difficult to maintain a planar crystal surface, causing the seed spot diameter to change and severely impacting the output power and laser beam quality.

[0033] To address the issue that existing disk laser multipass amplifiers can only operate at a fixed pump power and are sensitive to pump power fluctuations, this application proposes using a spot analysis device to monitor the spot diameter of the output laser and using a surface shape adjustment mirror to calibrate the spot diameter of the seed light in real time, forming a monitoring-correction active control optical path. This achieves a stable output spot diameter from low to high pump power and under power fluctuations, thereby ensuring the stability of the output laser power and beam quality.

[0034] The following is in conjunction with the appendix Figure 1 Detailed description of optional embodiments of the present invention.

[0035] like Figure 1 As shown, this application proposes a beam-actively controlled disk laser amplifier, comprising:

[0036] The disk crystal 5 is used to achieve laser amplification; for example, the disk crystal 5 is made of Yb:YAG with a doping concentration of 5%~20%, a diameter ≥10 mm, and a thickness of 100~500 µm. The function of the disk crystal 5 is to act as a laser gain medium, absorbing pump light and providing gain to the incident seed light.

[0037] Seed light source 1 is used to provide a polarized seed laser to be amplified. For example, the seed light source 1 has a wavelength of 1030±5nm and is horizontally polarized. The seed laser to be amplified has a first diameter spot at the disk crystal 5, and the size of the first diameter spot is dynamically adjustable.

[0038] A pumping device 6 is used to pump the disk crystal 5. The pump light emitted by the pumping device 6 has a second diameter spot at the disk crystal 5. Exemplarily, the pumping wavelength of the pumping device 6 is 940 nm or 969 nm, and its function is to direct the pump light onto the disk crystal 5, providing the disk crystal 5 with the required energy. In some embodiments, the pump light power of the pumping device is adjustable to adapt to different output laser power requirements, and the size of the second diameter spot is also adjustable with the output power. This necessitates that the diameter of the seed spot also be adjustable to improve the laser energy extraction efficiency.

[0039] A beam adjustment component is used to dynamically adjust the size of the first diameter beam spot of the seed light source 1 at the disk crystal 5, ensuring that the ratio of the first diameter beam spot to the second diameter beam spot is within a preset range. Because the disk-shaped gain crystal is very thin, typically 100-300 μm, the amplification of the seed light after a single pass is relatively small, requiring multiple passes to continuously extract pump energy. To ensure efficient energy extraction, the seed light needs to be incident on the pump center of the disk-shaped gain crystal each time, and the beam spot diameter of the seed light incident on the disk-shaped gain crystal needs to achieve an ideal match with the pump beam spot diameter to effectively extract pump energy. A seed beam spot that is too small will not extract pump energy completely, while a beam spot that is too large will experience absorption loss at the edges of the disk-shaped gain crystal, thus reducing extraction efficiency.

[0040] In some embodiments, the spot adjustment assembly includes a surface shape adjustment mirror 7, which is disposed in the laser amplification optical path. The size of the first diameter spot is dynamically adjusted by adjusting the surface shape of the surface shape adjustment mirror 7. For example, the radius of curvature of the reflecting surface of the surface shape adjustment mirror 7 varies from -0.2 to 0.2 m. -1 That is, the surface shape adjustment mirror 7 can continuously change between concave, planar, and convex surfaces to adjust the size of the first diameter spot so as to match the size of the pump spot. For example, the surface shape adjustment mirror 7 provides a continuously variable spherical surface shape from convex to planar to concave, which produces a diverging, converging, or constant effect on the divergence angle of the incident laser.

[0041] In some embodiments, the spot adjustment assembly further includes a spot analysis device 10, which is disposed outside the laser amplification optical path. The spot analysis device 10 has a photosensitive surface diameter ≥ 2 mm. The spot analysis device 10 controls the surface shape of the surface shape adjustment mirror 7 by analyzing the spot size of the output amplified laser, so as to dynamically adjust the size of the first diameter spot.

[0042] In some embodiments, controlling the surface shape of the surface shape adjustment mirror by analyzing the spot size of the amplified laser output to dynamically adjust the size of the first diameter spot includes: the spot analysis device 10 measures the spot diameter of the amplified laser output and compares it with a set value; if the measured spot diameter is less than the set value, the surface shape of the surface shape adjustment mirror 7 is controlled to be convex; if the measured spot diameter is greater than the set value, the surface shape of the surface shape adjustment mirror 7 is controlled to be concave, until the spot diameter monitored by the spot analysis device 10 is within the set value range. The set value can be determined through repeated experimental testing; it can be a fixed value or a range value, and is not limited thereto.

[0043] In some embodiments, the ratio of the first diameter spot to the second diameter spot is preset to a range of 0.7-0.8, for example, 0.75 or 0.77. Since the disk-shaped gain crystal is very thin, typically 100-300 μm, the amplification of the seed light after a single pass is small, requiring multiple passes to continuously extract pump energy. To ensure efficient energy extraction, the seed light needs to be incident on the pump center of the disk-shaped gain crystal each time, and the diameter of the seed light spot incident on the disk-shaped gain crystal needs to be equal to 0.7-0.8 times the diameter of the pump spot, thereby effectively extracting pump energy. A seed spot that is too small will not extract pump energy completely, while a spot that is too large will experience absorption loss at the edge of the disk-shaped gain crystal, thus reducing extraction efficiency.

[0044] In some embodiments, the seed laser to be amplified passes through a disk crystal at least 12 times to achieve amplified output. For example... Figure 1As shown, the seed laser emitted by the seed source 1 passes through the polarizing beam splitter 2 from left to right and is incident on the quarter-wave plate 3. The polarizing beam splitter 2 ensures high transmission of horizontally polarized laser light and high reflection of vertically polarized laser light. The angle between the incident light and the normal to the mirror is 45 degrees or 56 degrees. The diameter of the polarizing beam splitter is ≥10 mm, and the aperture of the quarter-wave plate is ≥1 mm, providing a π / 4 phase difference to the transmitted light. The quarter-wave plate 3 adjusts the polarization state of the transmitted seed light from horizontal to circular polarization. The seed light continues to be incident on the first 0-degree reflector 4-1 and reflected by it to the disk crystal 5. Passing through the disk crystal 5, the seed light energy is amplified through stimulated emission and is reflected by the disk crystal 5 to the second 0-degree reflector 4-6. This amplified seed light is called a laser. The laser beam is reflected by the second 0-degree reflector 4-6 to the surface shape adjustment mirror 7; the laser beam is reflected by the surface shape adjustment mirror 7 to the third 0-degree reflector 4-4; the laser beam is reflected by the third 0-degree reflector 4-4 to the disk crystal 5; the laser beam passes through the disk crystal 5, and through stimulated emission, the laser energy is further amplified and reflected by the disk crystal 5 to the fourth 0-degree reflector 4-3; the laser beam is reflected by the fourth 0-degree reflector 4-3 to the fifth 0-degree reflector 8; the laser beam is reflected by the fifth 0-degree reflector 8 to the sixth 0-degree reflector 4-2; the laser beam is reflected by the sixth 0-degree reflector 4-2 to the disk crystal 5; the laser beam passes through the disk crystal 5, and through stimulated emission, the laser energy is further amplified and reflected by the disk crystal 5 to the seventh 0-degree reflector 4-5; the laser beam is reflected by the seventh 0-degree reflector 4-5 to the surface shape adjustment mirror 7; the laser beam is reflected back along its original path by the surface shape adjustment mirror 7. The light then passes through the seventh 0-degree reflector 4-5, and in the opposite direction of the original optical path, sequentially through the disk crystal 5, the sixth 0-degree reflector 4-2, the 0-degree reflector 8, the fourth 0-degree reflector 4-3, the disk crystal 5, the third 0-degree reflector 4-4, the surface shape adjustment mirror 7, the second 0-degree reflector 4-6, the disk crystal 5, the first 0-degree reflector 4-1, and the quarter-wave plate 3. The quarter-wave plate 3 adjusts the polarization state of the transmitted laser from circular polarization to vertical polarization, and the laser is incident on the polarizing beam splitter 2. The polarizing beam splitter 2 reflects the laser to the first 45-degree reflector 9-1, where most of the laser (approximately >99.9%) is reflected and output by the first 45-degree reflector 9-1, and the remaining laser (approximately <0.1%) passes through the first 45-degree reflector 9-1 and is incident on the second 45-degree reflector 9-2. The second 45-degree reflector 9-2 reflects the laser to the spot analysis device 10. The spot analysis device 10 measures the diameter of the incident laser and compares it with a set value. If the measured spot diameter is less than the set value, a feedback signal is sent to the surface shape adjustment mirror 7, causing the surface shape adjustment mirror 7 to become convex; if the measured spot diameter is greater than the set value, a feedback signal is sent to the surface shape adjustment mirror 7, causing the surface shape adjustment mirror 7 to become concave, until the spot diameter monitored by the spot analysis device 10 is within the set value range. Each of the aforementioned 0-degree reflectors has a diameter ≥10 mm, and its function is to perform total internal reflection of laser light incident at 0±10 degrees.Each of the above 45-degree reflectors has a diameter ≥10 mm and its function is to perform total internal reflection of laser light incident at 45±10 degrees.

[0045] The active beam control disk laser amplifier provided in this application monitors the diameter of the output seed amplified laser spot using a spot analysis device and calibrates the spot diameter of the seed light in real time using a surface shape adjustment mirror, forming an active control optical path of monitoring and correction. This achieves a stable output spot diameter from low to high pump power and under power fluctuations, thereby ensuring the stability of the output laser power and beam quality.

[0046] Finally, it should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems or apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple; relevant parts can be referred to in the method section. This embodiment only describes an electromagnetic field structure designed using a Helmholtz coil and DC high voltage; other methods that utilize electromagnetic fields to confine plasma in a discharge region are within the scope of protection of this patent.

[0047] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A beam-actively controlled disk laser amplifier, characterized in that, include: Disc crystals are used to achieve laser amplification; A seed light source is used to provide a polarized seed laser to be amplified, wherein the seed laser to be amplified has a first diameter spot at the disk crystal, and the size of the first diameter spot is dynamically adjustable. A pumping device for pumping the disk crystal, wherein the pump light emitted by the pumping device has a second diameter spot at the disk crystal; The light spot adjustment component is used to dynamically adjust the size of the first diameter light spot so that the ratio of the first diameter light spot to the second diameter light spot is within a preset range.

2. The disk laser amplifier according to claim 1, characterized in that, The light spot adjustment component includes: A surface shape adjustment mirror is disposed in the laser amplification optical path, and the size of the first diameter light spot is dynamically adjusted by adjusting the surface shape of the surface shape adjustment mirror.

3. The disk laser amplifier according to claim 2, characterized in that, The light spot adjustment component also includes: A spot analysis device is installed outside the laser amplification optical path. It controls the surface shape of the surface shape adjustment mirror by analyzing the spot size of the output amplified laser, so as to dynamically adjust the size of the first diameter spot.

4. The disk laser amplifier according to claim 3, characterized in that, The step of controlling the surface shape of the surface shape adjustment mirror by analyzing the spot size of the amplified laser output, so as to dynamically adjust the size of the first diameter spot, includes: The spot analysis device measures the spot diameter of the amplified laser output and compares it with a set value. If the measured spot diameter is less than the set value, the surface shape of the surface adjustment mirror is controlled to be convex; if the measured spot diameter is greater than the set value, the surface shape of the surface adjustment mirror is controlled to be concave, until the spot diameter monitored by the spot analysis device is within the set value range.

5. The disk laser amplifier according to claim 2, characterized in that, The radius of curvature of the reflecting surface of the surface-adjusting mirror varies from -0.2 to 0.2 m. -1 .

6. The disk laser amplifier according to claim 1, characterized in that, The preset range is 0.7-0.

8.

7. The disk laser amplifier according to claim 1, characterized in that, The seed laser to be amplified passes through the disk crystal at least 12 times to achieve amplified output.

8. The disk laser amplifier according to claim 1, characterized in that, The disk crystal is made of Yb:YAG, with a doping concentration of 5% to 20%, a diameter of ≥10 mm, and a thickness of 100 to 500 µm.

9. The disk laser amplifier according to claim 3, characterized in that, Also includes: The output mirror reflects at least 99% of the amplified laser light, while the remaining less than 0.1% of the amplified laser light passes through the output mirror and enters the spot analysis device.

10. The disk laser amplifier according to claim 1, characterized in that, The pump light power of the pumping device is adjustable, and the size of the second diameter light spot is adjustable.

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