Laser beam combining system, method and laser beam combining apparatus

Abstract

A laser beam combining system, method and laser beam combining device, the system comprising a first optical path and a second optical path; the first optical path comprising a first wavelength selection element, a first frequency doubling element and a polarizer arranged in sequence along a first direction; the first direction being the initial transmission direction of a first laser beam emitted by a first laser; the second optical path comprising a second frequency doubling element, a second wavelength selection element and a third polarization adjustment element; the second frequency doubling element and the second wavelength selection element arranged in sequence along a second direction; the second wavelength selection element and the third polarization adjustment element arranged in sequence along a third direction; the specific angle being the angle at which the second frequency light coincides with the first frequency light after being reflected twice by the second wavelength selection element and the first wavelength selection element; the second direction being the initial transmission direction of the first laser beam emitted by the first laser; the third direction being the direction in which the second frequency light is reflected by the second wavelength selection element. The system enables high peak power output of two laser beams in time overlap.

Description

Technical Field

[0001] This application relates to the field of laser technology, and more specifically, to a laser beam combining system, method, and device. Background Technology

[0002] In applications such as industrial inspection and remote sensing, the synchronous excitation of multi-channel lasers is crucial to system performance. For example, technologies such as laser annealing, laser-induced breakdown spectroscopy, and lidar require multiple laser beams to possess sub-microradial level spatial pointing synchronization and nanosecond-level precise timing control capabilities. Utilizing the nonlinear effects of materials to combine laser beams is one such laser beam combining technique used for these tasks.

[0003] However, current second-order nonlinear beam combining techniques only satisfy the requirement that the generated sum-frequency pulse beams overlap spatially, not temporally. If the combined pulse beams overlap temporally, optical rectification (OR) occurs, meaning that the two temporally overlapping 532nm laser beams are partially reverse-converted into 1064nm laser beams. This affects the timing control capability of this beam combining technique. The reverse conversion ratio is related to the peak delay of the two pulses; the closer the peak values ​​of the two pulses are, the greater the reverse conversion ratio, reaching the reverse conversion threshold at a 0ns delay. To avoid reverse conversion in harmonic beam coaxial combining (HBCC), different pairs of pulses can be delayed in time. However, delaying the two pulses in time leads to a reduction in the peak power of the combined laser. This reverse conversion sets a final limit on the application performance of the second-order nonlinear process.

[0004] In other words, current laser beam combining technologies cannot achieve high peak power output when two laser beams overlap in time. Summary of the Invention

[0005] The purpose of this application is to provide a laser beam combining system, method, and equipment that, by adjusting the polarization direction of the combined laser beams using a polarization adjustment element, can achieve high peak power output when the two laser beams overlap in time.

[0006] In a first aspect, embodiments of this application provide a laser beam combining system, including a first optical path and a second optical path; the first optical path includes a first wavelength selection element, a first frequency doubling element, and an analyzer arranged sequentially along a first direction; the first wavelength selection element is used to transmit a first frequency light from a first laser emitted by a first laser to the first frequency doubling element; the first frequency doubling element is used to convert the frequency of the first frequency light and emit it to the analyzer; wherein, the first direction is the initial transmission direction of the first laser emitted by the first laser; the second optical path includes a second frequency doubling element, a second wavelength selection element, and a third polarization adjustment element; the second frequency doubling element and the second wavelength selection element are arranged sequentially along a second direction; the second wavelength selection element and the third polarization adjustment element are arranged sequentially along a second direction. The three directions are arranged sequentially; the second frequency doubling element is used to receive and convert the frequency of the second laser emitted by the second laser, and emit it to the second wavelength selection element; the second wavelength selection element is used to receive the second laser at a specific angle and reflect the second frequency light in the second laser towards the third polarization adjustment element; the third polarization adjustment element is used to adjust the polarization direction of the second frequency light and then transmit it to the first wavelength selection element; wherein, the specific angle is the angle at which the second frequency light coincides with the first frequency light after being reflected twice by the second wavelength selection element and the first wavelength selection element; the second direction is the initial transmission direction of the first laser emitted by the first laser; the third direction is the direction in which the second wavelength selection element reflects the second frequency light.

[0007] The aforementioned laser beam combining system adjusts the angle between the polarization directions of the two laser beams before they are converted into frequency-doubled light using a third polarization adjustment element. Based on the angle between the polarization directions detected by the analyzer and the energy loss of the laser beam after beam combining, the system can determine the correspondence between the polarization angle and the energy loss after beam combining. By adjusting the angle between the polarization directions of the two laser beams before beam combining based on this correspondence, the system can minimize the energy loss caused by optical rectification when the two laser beams overlap in time, thereby achieving high peak power output after laser beam combining.

[0008] In conjunction with the first aspect, optionally, the first optical path further includes a first polarization adjustment element; the first polarization adjustment element and the first wavelength selection element are arranged along the first direction; the first polarization adjustment element is used to receive and adjust the polarization reversal of the first laser before transmitting it to the first wavelength selection element.

[0009] The aforementioned laser beam combining system, by configuring a first polarization adjustment element in the first optical path to adjust the polarization direction of the first laser, makes the first laser phase-matched with the first frequency doubling element, thereby maximizing the efficiency of the first frequency doubling element in converting the first laser, and correspondingly, further maximizing the power output after laser beam combining.

[0010] In conjunction with the first aspect, optionally, the second optical path further includes a second polarization adjustment element; the second polarization adjustment element and the second frequency doubling element are arranged along the second direction; the second polarization adjustment element is used to receive and adjust the polarization reversal of the second laser before transmitting it to the second frequency doubling element.

[0011] The aforementioned laser beam combining system, by configuring a second polarization adjustment element in the second optical path to adjust the polarization direction of the second laser, makes the second laser phase-matched with the second frequency doubling element, thereby maximizing the efficiency of the second frequency doubling element in converting the second laser, and correspondingly, further maximizing the power output after laser beam combining.

[0012] In conjunction with the first aspect, optionally, the third direction is perpendicular to the first direction.

[0013] The aforementioned laser beam combining system, through a third optical path arrangement perpendicular to the first direction, ensures that the angle between the reflecting surface of the first frequency doubling element and the first direction is 45°, thus avoiding interference from cross-reflection or scattering caused by non-orthogonal arrangements. In other words, this effectively further increases the power output after laser beam combining.

[0014] In conjunction with the first aspect, optionally, the second direction is parallel to the first direction.

[0015] The aforementioned laser beam combining system, through an optical path layout where the second direction is parallel to the first direction, makes the arrangement directions of the second polarization adjustment element, the second frequency doubling element, and the second wavelength selection element parallel to the arrangement directions of the first polarization adjustment element and the first wavelength selection element, thereby making the layout of the entire laser beam combining system more compact and reducing space occupation.

[0016] In conjunction with the first aspect, optionally, the first wavelength selection element includes a first dichroic mirror; the second wavelength selection element includes a second dichroic mirror.

[0017] The aforementioned laser beam combining system, by employing a dichroic mirror as the wavelength selection element, achieves a laser transmittance of up to 95% and a reflectivity of up to 99%, thereby minimizing energy loss and maximizing the power output after laser beam combining. Furthermore, it simplifies the structure of the laser beam combining system and reduces its cost.

[0018] In conjunction with the first aspect, the third polarization adjustment element may optionally include a third half-wave plate.

[0019] The aforementioned laser beam combining system employs a third half-wave plate as the third polarization adjustment element, and correspondingly, a second half-wave plate as the second polarization adjustment element, and a first half-wave plate as the first polarization adjustment element. Since the half-wave plate can achieve polarization direction adjustment entirely based on its own physical properties, it does not require additional power supply, magnetic field, or complex control circuits, thus simplifying the structure of the laser beam combining system, reducing its cost, and simplifying the operation during the laser beam combining process by simply rotating the half-wave plate to adjust the polarization direction.

[0020] Secondly, this application provides a laser beam combining method applied to a laser beam combining system; wherein the laser beam combining system is used to combine a first laser emitted by a first laser and a second laser emitted by a second laser, and includes: an analyzer and a third polarization adjustment element; the method includes: independently activating the first laser to emit the first laser, recording the first polarization direction of the first laser detected by the analyzer; adjusting the third polarization adjustment element, and independently activating the second laser to emit the second laser, recording the second polarization direction of the second laser detected by the analyzer; wherein the first laser and the second laser have the same frequency; simultaneously activating the first laser and the second laser, detecting and determining the energy loss after the first laser and the second laser are combined; and adjusting the third polarization adjustment element to change the angle based on the angle between the first polarization direction and the second polarization direction and the corresponding energy loss, so as to minimize the value of the energy loss.

[0021] The laser beam combining method described above has the same beneficial effects as the laser beam combining system provided by the first aspect or any alternative embodiment of the first aspect, and will not be elaborated here.

[0022] In conjunction with the second aspect, optionally, adjusting the third polarization adjustment element to change the angle based on the angle between the first polarization direction and the second polarization direction and the corresponding energy loss to minimize the energy loss includes: performing Gaussian function regression analysis based on the angle and the corresponding energy loss to obtain an energy loss mathematical model; wherein the mathematical model characterizes the correspondence between the angle and the energy loss; using the energy loss mathematical model to determine the angle value corresponding to the minimum energy loss; and adjusting the first laser and the second laser to combine at the angle value.

[0023] The aforementioned laser beam combining method utilizes Gaussian regression analysis to obtain a mathematical model of energy loss that characterizes the relationship between the polarization direction angle and energy loss. This makes the final polarization direction angle determined to maximize the energy output after beam combining more accurate, and consequently, further improves the power output after laser beam combining.

[0024] Thirdly, this application provides a laser beam combining device, including a first laser, a second laser, and the laser beam combining system described in the first aspect; the laser output end of the first laser faces the first wavelength selection element; and the laser output end of the second laser faces the second frequency doubling element.

[0025] The laser beam combining device described above has the same beneficial effects as the laser beam combining system provided in the first aspect or any alternative embodiment of the first aspect, which will not be elaborated here. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a first schematic diagram of a laser beam combining system provided in an embodiment of this application;

[0028] Figure 2 This is a second schematic diagram of a laser beam combining system provided in an embodiment of this application;

[0029] Figure 3 A flowchart of a laser beam combining method provided in an embodiment of this application;

[0030] Figure 4 A diagram showing the relationship between the first loss ratio and pulse delay provided in an embodiment of this application;

[0031] Figure 5 A second relationship diagram between loss ratio and pulse delay is provided for embodiments of this application;

[0032] Figure 6 A detailed flowchart of step S180 in the laser beam combining method provided in this application embodiment;

[0033] Figure 7 This is a first schematic diagram of a laser beam combining device provided in an embodiment of this application;

[0034] Figure 8This is a second schematic diagram of a laser beam combining device provided in an embodiment of this application.

[0035] Icons: 100, Laser beam combining system; 110, First optical path; 1D, First wavelength selection element; 1C, First frequency doubling element; E, Analyzer; 1B, First polarization adjustment element; 120, Second optical path; 2C, Second frequency doubling element; 2D, Second wavelength selection element; 2B, Second polarization adjustment element; 3B, Third polarization adjustment element; 10, Laser beam combining device; 1A, First laser; 1B, Second laser. Detailed Implementation

[0036] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this application.

[0038] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0039] The technique of beam combining using second-order nonlinear effects allows pulses from multiple pulsed laser sources to be combined into a single spatial beam for multiplexing in the time domain, achieving frequency conversion (frequency doubling). This is achieved by utilizing the phase-matching properties of the frequency upconversion of a second-order nonlinear crystal in non-collinear interactions.

[0040] The light field incident on a second-order nonlinear optical medium consists of two distinct frequency components, which can be expressed as follows:

[0041]

[0042] The nonlinear polarization intensity then has the following form:

[0043]

[0044] For second harmonic generation (SHG), the polarization intensity can be expressed as:

[0045]

[0046] For difference frequency generation (SFG)

[0047]

[0048] When ω1=ω2, optical rectification (OR) occurs in the nonlinear crystal.

[0049]

[0050] Second harmonics (HHMs) are generated in nonlinear crystals, generally requiring angular phase matching. Because the fundamental and harmonic light incident on the crystal have different refractive indices, a phase difference occurs during their propagation. If the phases are out of sync, the newly generated light waves will interfere with each other, leading to reduced energy conversion efficiency or even complete cancellation. During HHM generation, if the fundamental wave is ordinary polarized and the second harmonic is extraordinary polarized, the refractive index of the fundamental wave lies between the two principal refractive indices of the second harmonic. Therefore, by choosing a suitable light propagation direction, phase matching can be achieved. This method of achieving phase matching by selecting a specific light propagation direction, resulting in different polarization states between the fundamental and second harmonics, is called angular phase matching.

[0051] Regarding the wavelength of the laser, nonlinear materials cut in a specific direction only generate frequency doubling for that specific wavelength; for lasers that do not meet the phase-matching condition, their wavelength remains unchanged. Regarding the polarization direction, second harmonics that meet the phase-matching condition maintain either o- or e-polarization, while the polarization direction of lasers that do not meet the phase-matching condition is determined by the crystal thickness. Based on these properties of nonlinear materials, the technique of second-order nonlinear effect beam combining can be realized. Under the influence of a strong laser, the SHG (Silicon-Glass Glycol) of a nonlinear material can convert a laser with a frequency of ω into a high-frequency laser with a polarization direction of 2ω, and the polarization direction of the frequency-doubled light remains constant. For example, crystals such as KTP, LBO, and KD*P can convert a 1064nm short-pulse infrared laser into 532nm green light with a fixed polarization direction of o or e.

[0052] Therefore, current second-order nonlinear beam combining techniques only satisfy the requirement that the generated radio frequency pulse beams overlap spatially, but not temporally. If the combined pulse beams overlap temporally, the frequency-doubled light after beam combining will inevitably undergo optical rectification in the nonlinear crystal, causing energy loss.

[0053] In view of this, this application provides a laser beam combining system, method, and device to solve the aforementioned technical problems. Specifically, please refer to the embodiments and accompanying drawings provided in this application.

[0054] Please refer to Figure 1 , Figure 1This is a first schematic diagram of a laser beam combining system 100 provided in this application embodiment. The laser beam combining system 100 provided in this application embodiment may include a first optical path 110 and a second optical path 120. The first optical path 110 may include a first wavelength selection element 1D, a first frequency doubling element 1C, and an analyzer E arranged sequentially along a first direction. The first wavelength selection element 1D can be used to transmit the first frequency light in the first laser emitted by the first laser 1A to the first frequency doubling element 1C. The first frequency doubling element 1C can be used to convert the frequency of the first frequency light and emit it to the analyzer E. The first direction may be the initial transmission direction of the first laser emitted by the first laser 1A. The second optical path 120 may include a second frequency doubling element 2C, a second wavelength selection element 2D, and a third polarization adjustment element 3B. The second frequency doubling element 2C and the second wavelength selection element 2D may be arranged sequentially along a second direction. The second wavelength selection element 2D and the third polarization adjustment element 3B may be arranged sequentially along a third direction. The second frequency doubling element 2C can be used to receive and convert the frequency of the second laser emitted by the second laser 1B, and then transmit it to the second wavelength selection element 2D. The second wavelength selection element 2D can be used to receive the second laser at a specific angle and reflect the second frequency light in the second laser towards the third polarization adjustment element 3B. The third polarization adjustment element 3B can be used to adjust the polarization direction of the second frequency light before transmitting it towards the first wavelength selection element 1D. The specific angle can be the angle at which the second frequency light coincides with the first frequency light after being reflected twice by the second wavelength selection element 2D and the first wavelength selection element 1D. The second direction can be the initial transmission direction of the first laser emitted by the first laser 1A. The third direction can be the direction in which the second wavelength selection element 2D reflects the second frequency light.

[0055] The first wavelength selection element 1D can be a dichroic mirror, grating, or prism, which selectively reflects or transmits light of a corresponding frequency based on different frequencies (or wavelengths) in the first laser. The analyzer E can be a linear polarizer, Glan-Taylor prism, etc. The first frequency doubling element 1C can be a KTP crystal, LBO crystal, BBO crystal, or PPLN crystal, etc., which have a second-order nonlinear effect, or it can be a second-order nonlinear crystal or a periodically polarized crystal. Taking a crystal with a second-order nonlinear effect as an example, it can convert a 1064nm short-pulse infrared laser into 532nm green light with a fixed polarization direction.

[0056] The second wavelength selection element 2D can specifically be a dichroic mirror, grating, or prism, which selectively reflects or transmits light of a corresponding frequency according to different frequencies (or wavelengths) in the second laser. The second frequency doubling element 2C can specifically be various crystals with second-order nonlinear effects, such as KTP crystals, LBO crystals, BBO crystals, or PPLN crystals, or second-order nonlinear crystals or periodically polarized crystals. The third polarization adjustment element 3B can specifically be a half-wave plate, optical rotator, etc.

[0057] The second wavelength selection element 2D, in addition to employing Figure 1 The optical path layout shown receives the second laser at a 45° incident angle, reflects it at a 45° reflection angle, and then incidents it again at a 45° incident angle onto the first wavelength selection element 1D. Finally, the first wavelength selection element 1D reflects the second laser at a 45° reflection angle, ensuring that the second frequency light coincides with the first frequency light after the first wavelength selection element 1D. The second wavelength selection element 2D can also employ methods such as... Figure 1 A layout other than the one shown in the diagram. For example, the second direction is parallel to the first direction. The second wavelength selection element 2D receives the second laser light at an incident angle of 60° and reflects it at a reflection angle of 60°. It then enters the first wavelength selection element 1D at an incident angle of 60°, and finally reflects it at a reflection angle of 60°, so that the second frequency light coincides with the first frequency light after the first wavelength selection element 1D. In this case, the reflecting surface of the second wavelength selection element 2D is usually parallel to the reflecting surface of the first wavelength selection element 1D, and the angle between it and the first direction is 30°. Of course, those skilled in the art can also use other optical layouts where the second direction is not parallel to the first direction, and adjust the tilt (i.e., the angle) of the reflecting surfaces of the first wavelength selection element 1D and the second wavelength selection element 2D relative to the first direction according to the rule that the incident angle equals the reflection angle during the reflection process, so that the second frequency light coincides with the first frequency light after being reflected twice by the second wavelength selection element 2D and the first wavelength selection element 1D.

[0058] The laser beam combining system 100 provided in this application embodiment operates as follows: For example, the first laser emitted by the first laser 1A is a 1064nm pulsed infrared laser. After passing through the first wavelength selection element 1D (taking a dichroic mirror as an example), based on the characteristics of the dichroic mirror reflecting frequency-doubled light and transmitting fundamental frequency light, the first frequency light reaching the first frequency doubling element 1C (taking a second-order nonlinear effect crystal as an example) is still a 1064nm pulsed infrared laser. After being converted by the first frequency doubling element 1C, it becomes a 532nm pulsed green laser, and finally reaches the analyzer E where the polarization direction of the 532nm pulsed green laser is detected. The second laser emitted by the second laser 1B is also a 1064nm pulsed infrared laser, which is converted by the second frequency doubling element 2C (again, taking a second-order nonlinear effect crystal as an example) into... A 532nm pulsed green laser light is emitted and then reaches the second wavelength selection element 2D (again, a dichroic mirror is used as an example). Based on the characteristics of the dichroic mirror—reflecting frequency-doubled light and transmitting fundamental light—and the optical path layout, the second wavelength selection element 2D adjusts the polarization direction of the 532nm pulsed green laser light (frequency-doubled light) through the third polarization adjustment element 3B, and then reflects it back to the first wavelength element. The second frequency light received by the first wavelength element is still a 532nm pulsed green laser light (frequency-doubled light), and is reflected again to the first frequency doubling element 1C. After passing through the first frequency doubling element 1C, it is still a 532nm pulsed green laser light (the second frequency light is usually not further converted into second-order frequency-doubled light when passing through the first frequency doubling element 1C). Finally, it reaches the analyzer E, where the polarization direction of the 532nm pulsed green laser light is detected. By turning on the first laser 1A and the second laser 1B respectively, and adjusting the polarization direction based on the polarization direction recorded by the analyzer E, the polarization direction between the first laser and the second laser is adjusted by adjusting the third polarization adjustment element 3B, thereby achieving the adjustment of the polarization angle between the first laser and the second laser. When both the first laser 1A and the second laser 1B are simultaneously activated, since both lasers become 532nm pulsed green lasers after passing through the first frequency doubling element 1C, the two lasers can be combined after passing through the first frequency doubling element 1C. By detecting and recording the angle between the polarization directions of the two lasers after adjustment by the third polarization adjustment element 3B, and the corresponding energy of the combined laser beams, the relationship between the polarization angle and the energy after beam combining can be determined. Consequently, the relationship between the polarization angle and the energy loss after beam combining can also be determined.

[0059] In the above implementation process, before the two laser beams to be combined are converted into frequency-doubled light, the angle between the polarization directions of the two laser beams is adjusted by the third polarization adjustment element 3B. Based on the angle between the polarization directions of the two laser beams detected by the analyzer E and the energy loss of the laser after beam combination, the correspondence between the polarization direction angle and the energy loss after beam combination can be determined. Based on this correspondence, the angle between the polarization directions of the two laser beams before beam combination is adjusted, so that the energy loss caused by optical rectification can be minimized when the two laser beams overlap in time, thereby achieving high peak power output after laser beam combination.

[0060] Please refer to Figure 2 , Figure 2 This is a second schematic diagram of the laser beam combining system 100 provided in this application embodiment. In some optional embodiments, the first optical path 110 may further include a first polarization adjustment element 1B. The first polarization adjustment element 1B and the first wavelength selection element 1D may be arranged along a first direction. The first polarization adjustment element 1B may be used to receive and adjust the polarization reversal of the first laser beam before it is transmitted to the first wavelength selection element 1D.

[0061] The first polarization adjustment element 1B can also be a half-wave plate, a rotator, etc. The polarization direction of the first laser can be adjusted by the first polarization adjustment element 1B to achieve phase matching with the first frequency doubling element 1C, thereby maximizing the conversion efficiency of the first frequency doubling element 1C on the first laser.

[0062] In the above implementation process, by configuring a first polarization adjustment element 1B in the first optical path 110 to adjust the polarization direction of the first laser, the first laser and the first frequency doubling element 1C are phase matched, thereby maximizing the efficiency of the first frequency doubling element 1C in converting the first laser, and correspondingly, further maximizing the power output after laser beam combining.

[0063] Please continue to refer to Figure 2 In some optional embodiments, the second optical path 120 may further include a second polarization adjustment element 2B. The second polarization adjustment element 2B and the second frequency doubling element 2C may be arranged along a second direction. The second polarization adjustment element 2B may be used to receive and adjust the polarization reversal of the second laser beam before it is transmitted to the second frequency doubling element 2C.

[0064] The second polarization adjustment element 2B can also be a half-wave plate, a rotator, or the like. The polarization direction of the second laser can be adjusted via the second polarization adjustment element 2B to achieve phase matching with the second frequency doubling element 2C, thereby maximizing the conversion efficiency of the second laser by the second frequency doubling element 2C.

[0065] It is easy to understand that, in this embodiment, although the second optical path 120 includes both a second polarization adjustment element 2B and a third polarization adjustment element 3B, their functions are different. Specifically, the second polarization element is used to adjust the polarization direction of the second laser to match its phase with the second frequency doubling element 2C, thereby maximizing the conversion efficiency of the second laser. The third polarization adjustment element is used to adjust the polarization direction of the second laser, thereby changing the angle between the polarization directions of the second and third lasers.

[0066] In the above implementation process, by configuring a second polarization adjustment element 2B in the second optical path 120, the polarization direction of the second laser is adjusted so that the second laser and the second frequency doubling element 2C are phase matched, thereby maximizing the efficiency of the second frequency doubling element 2C in converting the second laser. Correspondingly, the power output after laser beam combining is also maximized.

[0067] Please continue to refer to Figure 1 and Figure 2 In some alternative implementations, the third direction may be perpendicular to the first direction.

[0068] Since the third direction is perpendicular to the first direction, the second laser reflected by the second wavelength selection element 2D is perpendicular to the first laser reflected by the first wavelength selection element 1D. In this case, to ensure the second laser coincides with the first laser after being reflected twice by both the second wavelength selection element 2D and the first wavelength selection element 1D, the reflective surface of the first wavelength selection element 1D typically needs to form a 45° angle with the first direction. Correspondingly, the first laser is incident on the first wavelength selection element 1D at a 45° angle and reflected at a 45° angle, finally coinciding with the first laser, and then the two lasers merge after passing through the first frequency doubling element 1C.

[0069] Furthermore, regarding the second direction, no specific limitations are imposed on it in the embodiments of this application. Based on the foregoing description, those skilled in the art can determine any direction that allows the first laser and the second laser to coincide as the second direction, according to the rule that the angle of incidence equals the angle of reflection during the reflection process.

[0070] In the above implementation process, by using a third optical path layout perpendicular to the first direction, the angle between the reflective surface of the first frequency doubling element 1C and the first direction is 45°, avoiding interference from cross-reflection or scattering caused by non-orthogonal layout. In other words, this is equivalent to further improving the power output after laser beam combining.

[0071] Please continue to refer to Figure 1 and Figure 2In some alternative implementations, the second direction may be parallel to the first direction.

[0072] The second direction described in the preceding embodiments can be determined by those skilled in the art based on the rule that the angle of incidence equals the angle of reflection during the reflection process, and can be any direction that can make the first laser and the second laser coincide. In this embodiment, the second direction is limited to being parallel to the second direction.

[0073] Of course, in the embodiments of this application, the third direction may not be perpendicular to the first direction. For details, please refer to the example described above regarding the second wavelength selection element 2D receiving the second laser at an incident angle of 60°.

[0074] In this case, the angle between the reflecting surface of the second long selection element and the second direction (first direction) is 45°. The second laser is incident on the second long selection element at an angle of 45° and reflected back to the first long selection element at an angle of 45°.

[0075] In the above implementation process, by arranging the optical path with the second direction parallel to the first direction, the arrangement direction of the second polarization adjustment element 2B, the second frequency doubling element 2C, and the second wavelength selection element 2D is parallel to the arrangement direction of the first polarization adjustment element 1B and the first wavelength selection element 1D, thereby making the layout of the entire laser beam combining system 100 more compact and reducing the space occupied.

[0076] In some alternative implementations, the first wavelength selection element 1D may include a first dichroic mirror. The second wavelength selection element 2D may include a second dichroic mirror.

[0077] In the above implementation process, by specifically employing a dichroic mirror as the wavelength selection element, the laser transmittance reaches as high as 95% and the reflectivity reaches as high as 99%, thereby minimizing energy loss and maximizing the power output after laser beam combining. Furthermore, this simplifies the structure of the laser beam combining system 100 and reduces its cost.

[0078] In some alternative implementations, the third polarization adjustment element 3B may include a third half-wave plate.

[0079] In conjunction with the preceding embodiments, the first polarization adjustment element 1B can also be a first half-wave plate, and the second polarization adjustment element 2B can also be a second half-wave plate.

[0080] In the above implementation process, by specifically using a third half-wave plate as the third polarization adjustment element 3B, a second half-wave plate can also be specifically used as the second polarization adjustment element 2B, and a first half-wave plate can be specifically used as the first polarization adjustment element 1B. Since the half-wave plate can completely rely on its own physical characteristics to adjust the polarization direction, it does not need to rely on additional power supply, magnetic field or complex control circuit, etc., which simplifies the structure of the laser beam combining system 100, reduces the cost of the laser beam combining system 100, and the polarization direction can be adjusted by simply rotating the half-wave plate, which simplifies the operation in the laser beam combining process.

[0081] Please refer to Figure 3 , Figure 3 This is a flowchart of a laser beam combining method provided in an embodiment of this application. Based on the same concept, an embodiment of this application provides a laser beam combining method, which can be applied to the laser beam combining system 100 provided above, and may include:

[0082] Step S120: Turn on the first laser separately to generate the first laser, and record the first polarization direction of the first laser detected by the analyzer.

[0083] In step S120 above, when the laser beam combining system includes a first polarization adjustment element and a first frequency doubling element, the polarization direction of the first laser can be adjusted by the first polarization adjustment element so that its phase matches that of the first frequency doubling element, thereby maximizing the conversion efficiency of the first laser.

[0084] Step S140: Adjust the third polarization adjustment element and turn on the second laser separately to generate the second laser, and record the second polarization direction of the second laser detected by the analyzer.

[0085] In step S140 above, the first laser and the second laser have the same frequency. By adjusting the third polarization adjustment element, the angle between the polarization directions of the first laser and the second laser can be changed during subsequent beam combining. Similarly, when the laser beam combining system includes a second polarization adjustment element and a second frequency doubling element, the polarization direction of the second laser can be adjusted by the second polarization adjustment element to match its phase with that of the second frequency doubling element, thereby maximizing the conversion efficiency of the second laser.

[0086] Step S160: Simultaneously turn on the first laser and the second laser, and detect and determine the energy loss after the first laser and the second laser beam are combined.

[0087] In step S160 above, the preceding steps can be repeated several times, and the energy loss and corresponding polarization direction angle data after several beam combinations can be recorded accordingly, and a corresponding relationship can be established. For example, please refer to... Figure 4 and Figure 5, Figure 4 This is a graph showing the relationship between the first loss ratio and the pulse delay provided in the embodiments of this application; Figure 5 This is a graph showing the relationship between the second type of loss ratio and pulse delay provided in an embodiment of this application. From... Figure 4 and Figure 5 As can be seen, the loss ratio and the polarization direction angle are roughly normal within a specific range of 90°.

[0088] Step S180: Based on the angle between the first polarization direction and the second polarization direction and the corresponding energy loss, adjust the third polarization adjustment element to change the angle so as to minimize the energy loss.

[0089] In step S180 above, the polarization direction angle corresponding to the condition of minimum energy loss after beam combining can be determined based on the correspondence established in step S160. For example: Figure 5 The 90° shown.

[0090] The above implementation process is the same as that of the laser beam combining system described above, and will not be repeated here.

[0091] Please refer to Figure 6 , Figure 6 This is a flowchart illustrating step S180 in the laser beam combining method provided in this application. In some optional implementations, step S180 may include:

[0092] Step S181: Perform Gaussian function regression analysis based on the included angle and the corresponding energy loss to obtain the mathematical model of energy loss.

[0093] In step S181 above, the mathematical model represents the correspondence between the included angle and energy loss. Based on... Figure 4 For example, it can be observed that the relationship between the energy and energy loss after laser beam combining and the polarization angle is basically a normal distribution, i.e., a Gaussian distribution. Therefore, a Gaussian function can be used as an initial mathematical model. By performing Gaussian regression analysis on the collected data to this initial mathematical model, a more specific mathematical relationship between the energy and energy loss after laser beam combining and the polarization angle can be determined, resulting in an energy loss mathematical model.

[0094] Step S182: Use the energy loss mathematical model to determine the angle value corresponding to the minimum energy loss.

[0095] In step S182 above, based on the more specific mathematical model determined in the preceding steps, the angle between the polarization directions corresponding to the minimum energy loss can be determined. This allows us to determine the angle between the polarization directions of the first and second lasers under the condition of high peak power output after laser beam combining.

[0096] Step S183: Adjust the first laser and the second laser to combine them at an angle.

[0097] In the above implementation process, a mathematical model of energy loss is obtained by using Gaussian regression analysis to characterize the relationship between the polarization direction angle and energy loss. This makes the final polarization direction angle determined to maximize the energy output after beam combining more accurate, and correspondingly, further improves the power output after laser beam combining.

[0098] Please refer to Figure 7 and Figure 8 , Figure 7 This is a first schematic diagram of the laser beam combining device 10 provided in the embodiments of this application; Figure 8 This is a second schematic diagram of the laser beam combining device 10 provided in this application embodiment. Based on the same concept, this application embodiment provides a laser beam combining device 10, which may include a first laser 1A, a second laser 1B, and the laser beam combining system 100 described above. The laser output end of the first laser 1A may be directed toward the first wavelength selection element 1D. The laser output end of the second laser 1B may be directed toward the second frequency doubling element 2C.

[0099] The above implementation process is the same as that of the laser beam combining system 100 described above, and will not be repeated here.

[0100] This application also provides a storage medium, which includes a computer-readable storage medium. A computer program is stored on the computer-readable storage medium, and the computer program is executed by a processor to perform the methods described above.

[0101] The computer-readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read Only Memory (EPROM), Programmable Red-Only Memory (PROM), Read-Only Memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk.

[0102] It should be understood that the disclosed apparatus and methods can also be implemented in other ways, given the several embodiments provided in this application. The apparatus embodiments described above are merely illustrative. For example, the flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code, which contains one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, or they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram and / or flowchart, and combinations of blocks in block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0103] In addition, the functional modules in the various embodiments of this application can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0104] The above description is only an optional implementation of the embodiments of this application, but the protection scope of the embodiments of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the embodiments of this application should be covered within the protection scope of the embodiments of this application.

Claims

1. A laser beam combining system, characterized in that, Including the first optical path and the second optical path; The first optical path includes a first wavelength selection element, a first frequency doubling element, and a polarizer arranged sequentially along a first direction; The first wavelength selection element is used to transmit the first frequency light in the first laser emitted by the first laser to the first frequency doubling element; The first frequency doubling element is used to convert the frequency of the first frequency light and emit it towards the analyzer; wherein, the first direction is the initial transmission direction of the first laser emitted by the first laser. The second optical path includes a second frequency doubling element, a second wavelength selection element, and a third polarization adjustment element; the second frequency doubling element and the second wavelength selection element are arranged sequentially along a second direction; the second wavelength selection element and the third polarization adjustment element are arranged sequentially along a third direction. The second frequency multiplier element is used to receive and convert the frequency of the second laser emitted by the second laser, and then transmit it to the second wavelength selection element; The second wavelength selection element is used to receive the second laser at a specific angle and reflect the second frequency light in the second laser toward the third polarization adjustment element; The third polarization adjustment element is used to adjust the polarization direction of the second frequency light before it is transmitted to the first wavelength selection element. Wherein, the specific angle is the angle at which the second frequency light coincides with the first frequency light after being reflected twice by the second wavelength selection element and the first wavelength selection element; the second direction is the initial transmission direction of the first laser emitted by the first laser; and the third direction is the direction in which the second wavelength selection element reflects the second frequency light. The first optical path also includes a first polarization adjustment element; The first polarization adjustment element and the first wavelength selection element are arranged along the first direction; The first polarization adjustment element is used to receive and adjust the polarization reversal direction of the first laser beam transmitted through the first wavelength selection element.

2. The laser beam combining system according to claim 1, characterized in that, The second optical path also includes a second polarization adjustment element; The second polarization adjustment element and the second frequency doubling element are arranged along the second direction; The second polarization adjustment element is used to receive and adjust the polarization reversal direction of the second laser beam transmitted by the second frequency doubling element.

3. The laser beam combining system according to claim 1, characterized in that, in, The third direction is perpendicular to the first direction.

4. The laser beam combining system according to claim 3, characterized in that, in, The second direction is parallel to the first direction.

5. The laser beam combining system according to claim 1, characterized in that, The first wavelength selection element includes a first dichroic mirror; The second wavelength selection element includes a second dichroic mirror.

6. The laser beam combining system according to claim 1, characterized in that, The third polarization adjustment element includes a third half-wave plate.

7. A method for laser beam combining, characterized in that, The laser beam combining system described in claim 1 is used to combine a first laser emitted by a first laser and a second laser emitted by a second laser, and includes: an analyzer and a third polarization adjustment element. The method includes: The first laser is activated independently to generate the first laser, and the first polarization direction of the first laser detected by the analyzer is recorded. Adjust the third polarization adjustment element and turn on the second laser separately to generate the second laser, and record the second polarization direction of the second laser detected by the analyzer; wherein the first laser and the second laser have the same frequency; Simultaneously activate the first laser and the second laser, detect and determine the energy loss after the first laser and the second laser beam are combined; and Based on the angle between the first polarization direction and the second polarization direction and the corresponding energy loss, the third polarization adjustment element is adjusted to change the angle so as to minimize the energy loss.

8. The method according to claim 7, characterized in that, The step of adjusting the third polarization adjustment element to change the angle between the first polarization direction and the second polarization direction and the corresponding energy loss, so as to minimize the energy loss, includes: Gaussian function regression analysis is performed based on the included angle and the corresponding energy loss to obtain a mathematical model of energy loss; wherein, the mathematical model represents the correspondence between the included angle and the energy loss; The included angle value corresponding to the minimum energy loss is determined using the energy loss mathematical model; and The first laser and the second laser are adjusted to combine at the stated angle value.

9. A laser beam combining device, characterized in that, Includes a first laser, a second laser, and a laser beam combining system as described in any one of claims 1 to 6; The laser output end of the first laser is oriented toward the first wavelength selection element; The laser output end of the second laser is oriented toward the second frequency doubling element.

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