Multi-wavelength pulse laser output device with synchronous time sequence

Abstract

The invention belongs to the technical field of laser, and provides a time sequence synchronous multi-wavelength pulse laser output device, which comprises a plurality of groups of optical gain modules, each group of optical gain modules comprises a blazed grating and a laser gain tube, each blazed grating is configured to reflect incident light with a set wavelength into the laser gain tube, and each blazed grating is configured to reflect the incident light with the set wavelength into the laser gain tube. Each group of light splitting gain modules are used for forming laser with different wavelengths; the acousto-optic modulator is configured to enable the multiple groups of gained multi-wavelength lasers to be incident to the acousto-optic modulator to meet the Bragg condition and then enable the pulse lasers to be synchronously output in time sequence, and at least every two groups of lasers are incident to the same position of the acousto-optic modulator; each group of output mirrors is plated with a semi-transparent and semi-reflective film and forms a resonant cavity with one group of blazed gratings, a laser part returns to the laser gain tube through the output mirrors along the same path and forms resonance with the blazed gratings, and a laser part is transmitted through the output mirrors; and the beam combining grating is used for combining the pulse lasers with different wavelengths and then outputting the combined pulse lasers at the same emergent angle.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of laser amplifiers, in particular to a time sequence synchronized multi-wavelength pulse laser output device. BACKGROUND

[0002] Extreme ultraviolet radiation (EUV) lithography machine is a bright pearl jointly created by modern industrial system and technological wisdom of human beings, and the EUV light source is one of the core subsystems of the lithography machine. The only commercialized technology for obtaining high-power EUV light source at present is to generate 13.5 nm extreme ultraviolet light by irradiating a liquid droplet tin target with a CO2 laser having high repetition frequency, short pulse width and high power. The Master Oscillator Power-Amplifier (MOPA) technology is usually adopted, that is, a seed light source with high repetition frequency and short pulse width is amplified by multiple stages to realize high-power laser output. Since the CO2 molecule has multiple non-continuous gain spectra, if multiple wavelength seeds matched with the peak values of the laser gain spectrum are used for synchronous gain extraction, the power amplification effect will be greatly improved, thereby improving the amplification efficiency of the laser system.

[0003] At present, the multi-wavelength tunable pulse CO2 laser reported usually adopts multiple Q-switching devices to realize laser pulse output, and dynamic rotating gratings, prisms and other light splitting elements are used to select laser resonant output of different wavebands. This technical means has the problems of poor time synchronization accuracy of short pulse laser and low multi-wavelength light splitting accuracy, which further affects the amplification efficiency of the seed laser and the final EUV light conversion efficiency.

[0004] Therefore, a time sequence synchronized multi-wavelength pulse laser output device is provided to solve one of the above technical problems. SUMMARY

[0005] The purpose of the present application is to provide a time sequence synchronized multi-wavelength pulse laser output device, which can solve at least one of the above technical problems. The specific scheme is as follows: According to the specific embodiment of the present application, a time sequence synchronized multi-wavelength pulse laser output device comprises: a plurality of light splitting gain modules, each of the light splitting gain modules comprising a blazed grating and a laser gain tube, each of the blazed gratings being configured to reflect incident light of a set wavelength into the laser gain tube, each of the light splitting gain modules being used to form laser light of different wavelengths, and the difference between each of the laser wavelengths being less than 0.02 μm; an acousto-optic modulator configured to make the plurality of gain-processed multi-wavelength laser lights incident into the acousto-optic modulator to satisfy the Bragg condition, so as to make each of the pulse laser lights time sequence synchronized output, wherein at least two of the laser lights are incident into the same position of the acousto-optic modulator; One or more sets of output mirrors, each set of the output mirrors being coated with a half-transmission half-reflection film, and forming a resonant cavity with a set of the blazed gratings respectively, the laser light of the set wavelength partially returning to the laser gain tube through the output mirrors, resonating with the blazed gratings, and partially transmitting through the output mirrors; A beam-combining grating, which outputs the pulsed laser beams of different wavelengths at the same exit angle after the pulsed laser beams of different wavelengths are combined.

[0006] In some embodiments, the beam-combining grating is located outside the resonant cavity, and the pulsed laser beams of different wavelengths are output from the output mirrors and then respectively incident on the beam-combining grating to be combined.

[0007] In some embodiments, the beam-combining grating is located inside the resonant cavity, and the pulsed laser beams of different wavelengths are respectively incident on the beam-combining grating to be combined and then output from the output mirrors.

[0008] In some embodiments, the laser wavelengths include CO2 laser spectral lines in the range of 9 μm-11 μm.

[0009] In some embodiments, the multiple sets of partial light gain modules are four sets, two sets of laser light are respectively incident on a first position of the acousto-optic modulator to satisfy the Bragg condition, and the other two sets of laser light are respectively incident on a second position of the acousto-optic modulator to satisfy the Bragg condition, and the distance between the first position and the second position is L.

[0010] In some embodiments, the distance L between the first position and the second position is less than 80% of the light aperture of the acousto-optic modulator.

[0011] In some embodiments, the distance d between the first position and the second position is 15 mm-16 mm.

[0012] In some embodiments, the diffraction efficiency of the blazed grating and / or the beam-combining grating in the 9 μm~11 μm waveband is >90%.

[0013] In some embodiments, the laser wavelengths are 10.57 μm and 10.59 μm, the incident angle of the corresponding beam-combining grating in the 10.57 μm waveband is , the incident angle of the corresponding beam-combining grating in the 10.59 μm waveband is , and the diffraction angle of the beam-combining grating is 31.94°; the incident angle of the blazed grating corresponding to the 10.57 μm waveband is 31.90°, and the incident angle of the blazed grating corresponding to the 10.59 μm waveband is 31.97°.

[0014] In some embodiments, the laser wavelengths are any four sets of CO2 laser spectral lines in the range of 9 μm-11 μm.

[0015] Compared with the prior art, the above-described solutions of this application have at least the following beneficial effects: The device provided in this application solves the problem of poor time synchronization of short-pulse lasers in multi-wavelength beam combining in current EUV seed light sources, thereby improving seed light power amplification efficiency and EUV light conversion efficiency. It also addresses the issue of inconsistent pulse laser timing caused by multiple Q-switching devices operating independently, resulting in better pulse timing consistency and a better pulse waveform after spectral beam combining. Furthermore, it solves the problems of low separation capability for similar wavelengths and poor wavelength selection accuracy during prism beam splitting (e.g., dual wavelengths of 10.57μm and 10.59μm), improving the temporal overlap of short-pulse multi-wavelength CO2 laser pulse peaks, as well as wavelength selection capability and accuracy. This application utilizes an acousto-optic modulator to ensure simultaneous Q-switching of multiple wavelength lasers, achieving synchronized output of multiple wavelength short-pulse lasers. It simultaneously solves the two core problems of time synchronization and pulse modulation, significantly reducing system complexity. Using the acousto-optic modulator as a hub, it achieves integrated control of "time synchronization-pulse modulation-spatial beam combining" for multi-wavelength CO2 lasers, overcoming the technical bottleneck of asynchronous or off-axis output of multiple wavelengths in traditional solutions. This application can be widely used in the fields of laser material processing, infrared countermeasures / jamming, lidar, and laser medicine. Attached Figure Description

[0016] 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: Figure 1 A schematic diagram of a timing-synchronized multi-wavelength pulsed laser output device provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the working principle of the acousto-optic modulator provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of beam combining and output provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of a four-wavelength time-synchronized pulse laser output device provided in an embodiment of the present invention.

[0017] Explanation of reference numerals in the attached figures: In the diagram: 1. First blazed grating, 2. Second blazed grating, 3. First laser gain tube, 4. Second laser gain tube, 5. First folding mirror, 6. Second folding mirror, 7. Acousto-optic modulator, 8. Third folding mirror, 9. Fourth folding mirror, 10. Second output mirror, 11. First output mirror, 12. Fifth folding mirror, 13. Sixth folding mirror, 14. Beam combiner grating, 15. Seventh folding mirror, 16. Third blazed grating, 17. Fourth blazed grating, 18. Third laser gain tube, 19. Fourth laser gain tube, 20. Eighth folding mirror, 21. Ninth folding mirror, 22. Tenth folding mirror, 23. Eleventh folding mirror, 24. Third output mirror, 25. Fourth output mirror, 26. Twelfth folding mirror, 27. Thirteenth folding mirror, 28. Fourteenth folding mirror. Detailed Implementation

[0018] 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.

[0019] 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.

[0020] In the related technologies of multi-wavelength tunable pulsed CO2 lasers, a method can be used to split laser light of different wavelengths into two beams, with each beam corresponding to an independent laser gain tube, thereby achieving coaxial output of dual-wavelength CO2 seed lasers. However, prism beam splitting has difficulty distinguishing two closely spaced wavelengths, such as 10.57μm and 10.59μm, which limits the application of combining adjacent wavelengths of CO2 laser beams. Moreover, the accuracy of prism beam splitting is relatively poor, and the process of using a reflector to guide different wavelength beams can easily introduce stray light, limiting its application in higher-precision environments. Furthermore, grating-tuned multi-wavelength lasers are limited by the inability of the separate modulation devices to switch synchronously, failing to solve the problem of synchronous output of short-pulse lasers.

[0021] This application provides a time-synchronized multi-wavelength pulsed CO2 laser output device. Multiple blazed gratings are used for wavelength selection, and each laser beam corresponds to an independent laser gain tube after wavelength selection, solving the problem of difficult beam splitting with prisms of similar wavelengths. Then, the laser beams are Q-switched using a single acousto-optic modulator to obtain multi-wavelength, short-pulse lasers with good time synchronization. Finally, spectral beam combining based on beam splicing achieves coaxial output of the multi-wavelength lasers. Because multiple gratings are used for wavelength selection, multiple wavelengths of light are incident along both sides of the modulator normal, thus separating lasers with smaller wavelength differences within the CO2 laser gain spectrum. Simultaneously, the use of a common Q-switching device for the multi-wavelength lasers results in better pulse timing consistency and a better pulse waveform after spectral beam combining, effectively ensuring EUV light conversion efficiency.

[0022] The following is in conjunction with the appendix Figures 1-4 Detailed description of optional embodiments of the present invention.

[0023] According to specific embodiments of the present invention, this application provides a timing-synchronized multi-wavelength pulsed laser output device, such as... Figure 1 As shown, it includes: The system comprises multiple beam-splitting gain modules, each group including a blazed grating and a laser gain tube. Each blazed grating is configured to reflect incident light of a set wavelength into the laser gain tube, while incident light of other wavelengths is diffracted and lost, thereby achieving wavelength selection. Each group of beam-splitting gain modules is used to generate lasers of different wavelengths, with the wavelength difference between each laser being less than 0.02 μm. The laser gain tube amplifies the incident light of the set wavelength. For example, the 10.57 μm and 10.59 μm bands of CO2 laser are selected as two set wavelengths. The optical gain module has two groups. The first beam splitting gain module includes a first blazed grating 1 and a first laser gain tube 3. The second beam splitting gain module includes a second blazed grating 2 and a second laser gain tube 4. Both the first laser gain tube 3 and the second laser gain tube 4 adopt a fully external cavity design, and both ends are sealed with high-transmittance window mirrors. The first laser gain tube 3 and the second laser gain tube 4 provide gain for CO2 lasers in the 10.57μm and 10.59μm bands, respectively. The first laser gain tube 3 and the second laser gain tube 4 are radio frequency waveguide laser gain tubes, and their inner aperture is 3mm.

[0024] The acousto-optic modulator 7 is configured to receive multiple groups of multi-wavelength lasers after gaining their beams to satisfy the Bragg condition. Each group of lasers is then Q-switched by the modulator. Due to the use of a common Q-switching device, the multi-wavelength pulsed lasers can be naturally and precisely aligned in the time dimension. At least two groups of lasers are incident on the same position within the acousto-optic modulator. The acousto-optic modulator 7 generates ultrasonic waves through an acousto-electric transducer. When the ultrasonic waves act on the acousto-optic crystal in the modulator 7, the refractive index of the acousto-optic crystal undergoes a periodic change, causing the laser beam passing through the crystal to diffract and deviate from its original propagation direction. At this point, the resonant cavity loss increases, preventing oscillation and causing the number of inverted particles to accumulate. When the ultrasound is removed, the acousto-optic crystal returns to a uniform state, allowing the laser to pass through normally and form resonance. The accumulated inverted particles are released synchronously, generating a high-peak-power pulse output. For example, under the precise control of the folding mirror optical path, the first and second beam splitting gain modules share the same acousto-optic modulator 7. This ensures that the two wavelength lasers can be Q-switched simultaneously, achieving synchronous output of two short-pulse lasers of different wavelengths. This solves both the time synchronization and pulse modulation issues, significantly reducing system complexity. The acousto-optic modulator 7 changes the direction of the outgoing light by altering the voltage state. The incident light is incident strictly according to the Bragg condition. When the voltage is applied, the outgoing light is concentrated in the direction of the first-order diffraction, causing the light to deflect out of the resonant cavity. The resonant cavity loss is high, and the number of inverted particles continues to accumulate. When the voltage is disconnected, diffraction does not occur, and the light exits along the direction of the 0th order. At this point, the loss drops sharply, generating a high-peak-power pulse output. The first folding mirror 5 and the second folding mirror 6 respectively introduce lasers with wavelengths of 10.57μm and 10.59μm, which are output along the two sides of the normal of the acousto-optic modulator 7, and the two laser beams are modulated at the same time.

[0025] For example, CO2 laser light at wavelengths of 10.57 μm and 10.59 μm is incident from the same point on both sides of the normal of the acousto-optic modulator 7, each with its own Bragg condition, such as... Figure 2 As shown, let the angle between the incident light and the crystal normal of the acousto-optic modulator 7 be α. In the formula It is the wavelength of light in a vacuum. It is the wavelength of the sound wave. b It is the Bragg angle within the crystal. c is the angle between the first-order diffracted light within the crystal and the crystal normal of the acousto-optic modulator 7. d is the angle between the 0th order emitted beam and the normal when no voltage is applied. e is the angle between the first-order emitted ray and the crystal normal. Here, n1 represents the crystal refractive index, and n2 represents the air refractive index. The Bragg angle for the 10.57μm band is 0.5502°, and the Bragg angle for the 10.59μm band is 0.5517°. Using the law of refraction, the incident angles for the two bands are 2.202° and 2.206°, respectively, and the exit angle is the same as the incident angle. The exit separation angle is 4.408°. At a distance of 300mm from the acousto-optic modulator 7, the beam splitting distance reaches 23.08mm, providing sufficient space to insert the third and fourth folding mirrors 8 and 9, respectively, to guide the two laser beams to the second output mirror 10 and the first output mirror 11 for output. The crystal of the acousto-optic modulator 7 is a germanium crystal. The refractive index in the infrared band is approximately 4, the operating wavelength is 9-11μm, and it can generate ultrasonic waves with a wavelength of 137.5μm.

[0026] One or more sets of output mirrors, such as the second output mirror 10 and the first output mirror 11, each set of output mirrors is coated with a semi-transparent and semi-reflective film, and each set of output mirrors forms a resonant cavity with a set of blazed gratings. The laser of the set wavelength is partially returned to the blazed grating gain through the output mirrors, and partially transmitted through the output mirrors. For example, the output mirrors are ZnSe plane mirrors.

[0027] A beam combiner grating 14 combines pulsed laser beams of different wavelengths and outputs them at the same exit angle. Specifically, it achieves beam combining by precisely controlling the incident angles of multiple beams of different wavelengths, ensuring that their diffracted beams are in the same direction. For example, the beam combiner grating 14 has a line density of 100 lines / mm, a diffraction efficiency >90% in the 9-11μm band, and a grating constant of [missing information]. grating equation m is the diffraction order, taken as... , It is the angle of incidence. It is the diffraction angle. The blaze angle is used as the diffraction angle. When the angle of incidence is 31.94°, then the incident angle in the 10.57μm band is... The incident angle in the 10.59μm band They ultimately launch at a common launch angle, achieving beam convergence.

[0028] In some embodiments, the beam combiner grating 14 is located outside the resonant cavity, and pulsed lasers of different wavelengths are output from the output mirror and then incident on the beam combiner grating 14. For example... Figure 1As shown, the internal optical path of the resonant cavity is as follows: the CO2 laser passes through the first blazed grating 1, selects the incident light with a wavelength of 10.57 μm, and returns to the first laser gain tube 3 after self-collimation. The light emitted from the first laser gain tube 3 is precisely deflected by the first folding mirror 5 and incident on the acousto-optic modulator 7 under the Bragg condition. The pulsed laser emitted from the acousto-optic modulator 7 is then guided to the first output mirror 11 through the fourth folding mirror 9. The portion of the light satisfying the laser resonance condition is output, while the portion returns to the first blazed grating 1 along the original path. Each wavelength in the device corresponds to a set of resonant cavities. At the same time, the second blazed grating 2, the second laser gain tube 4, the second folding mirror 6, the acousto-optic modulator 7, the third folding mirror 8, and the second output mirror 10 form a resonant cavity corresponding to the wavelength of 10.59 μm. The two wavelength lasers output from the two resonant cavities are then incident on the beam combining grating 14 at a specific angle through the fifth folding mirror 12 and the sixth folding mirror 13, realizing multi-wavelength laser coaxial output. It ensures that the resonant feedback maintains oscillation while achieving partial output, thus improving energy extraction efficiency. The resonant cavity structure is simple, and each wavelength is independently tuned without affecting each other, making it easy to independently optimize the resonant cavity parameters of each branch. All the folding mirrors are plane mirrors, and the elevation and azimuth angles are adjustable.

[0029] In some embodiments, the beam combiner grating 14 is located within the resonant cavity, and pulsed lasers of different wavelengths are incident on the beam combiner grating 14 and then output from the output mirror. For example... Figure 3 As shown, the internal optical path of the resonant cavity is as follows: the CO2 laser passes through the first blazed grating 1, selects the 10.57μm incident light, and returns to the first laser gain tube 3 after self-collimation. The light emitted from the first laser gain tube 3 is precisely deflected by the first folding mirror 5 and incident on the acousto-optic modulator 7 under the Bragg condition. The pulsed laser emitted from the acousto-optic modulator 7 is then guided into the beam combiner grating 14 through the fourth folding mirror 9 and the sixth folding mirror 13. Simultaneously, the 10.59μm laser is also guided into the beam combiner grating 14 through the second blazed grating 2, the second laser gain tube 4, the second folding mirror 6, the acousto-optic modulator 7, the third folding mirror 8, and the fifth folding mirror 12. The two wavelength lasers are incident on the beam combiner grating 14 at a preset angle, achieving coaxial beam combining of multi-wavelength lasers, and then output from the second output mirror 10. By placing the beam combiner grating 14 inside the resonant cavity, more space is available to arrange the third folding mirror 8, the fifth folding mirror 12, the fourth folding mirror 9, and the sixth folding mirror 13. At this time, there is only one output mirror, which is coaxial with the beam combiner grating 14, making the device structure more compact.

[0030] In some embodiments, each laser wavelength includes CO2 laser spectral lines in the range of 9μm-11μm. For example, when the set wavelength of the incident light is 10.57μm and 10.59μm, the beam splitting gain module includes two blazed gratings. The incident angle of the first blazed grating 1 for the 10.57μm band is 31.90°, and the incident angle of the second blazed grating 2 for the 10.59μm band is 31.97°. The first blazed grating 1 and the second blazed grating 2 reflect light with wavelengths of 10.57μm and 10.59μm by adjusting their angles, achieving wavelength selection. For example, the blazed gratings satisfy: ,in d It is the grating constant. θ is the angle between the incident light and the normal, and it is also the angle between the outgoing light and the normal. m is the diffraction order. This refers to setting the wavelength. The first blazed grating 1 and the second blazed grating 2 have a grating density of 100 lines / mm and a diffraction efficiency >90% in the 9μm~11μm wavelength range. The first blazed grating 1 and the second blazed grating 2 employ a Littrow structure, characterized by equal incident and exit angles. Light of the set wavelength, after being incident on the first blazed grating 1 and the second blazed grating 2, returns along the same path. d =10μm; m is taken as the first-order diffraction light; It sets the wavelength. A precise incident angle ensures the grating operates near the blaze angle, greatly improving diffraction efficiency.

[0031] In some embodiments, the multi-component optical gain module comprises four groups, wherein two groups of lasers satisfy the Bragg condition and are incident on the first position of the acousto-optic modulator 7, and the other two groups of lasers satisfy the Bragg condition and are incident on the second position of the acousto-optic modulator 7, respectively, with the aim of separating two beams that are not at the same incident point but have similar directions. Figure 4As shown, a first blazed grating 1, a first laser gain tube 3, a first folding mirror 5, an acousto-optic modulator 7, a fourth folding mirror 9, and a first output mirror 11 form a first oscillating laser. The output laser is reflected onto a beam combiner grating 14 via a sixth folding mirror 13. A second blazed grating 2, a second laser gain tube 4, a second folding mirror 6, an acousto-optic modulator 7, a third folding mirror 8, and a second output mirror 10 form a second oscillating laser. The output laser is reflected onto a beam combiner grating 14 via a fifth folding mirror 12 and a seventh folding mirror 15. The first and second oscillating lasers are both at the first position at the incident point of the acousto-optic modulator 7. Similarly, a third blazed grating 16, a third laser gain tube 18, an eighth folding mirror 20, an acousto-optic modulator 7, a tenth folding mirror 22, and a third output mirror 24 form a third oscillating laser. The output laser is reflected onto a beam combiner grating 14 via a twelfth folding mirror 26 and a fourteenth folding mirror 28. The fourth blazed grating 17, the fourth laser gain tube 19, the ninth toggle mirror 21, the eleventh toggle mirror 23, and the fourth output mirror 25 form the fourth oscillating laser. The output laser is reflected by the thirteenth toggle mirror 27 onto the beam combiner grating 14. The third and fourth oscillating lasers are both at the second position of the acousto-optic modulator 7. The distance between the first and second positions is L. The dual-position incidence is limited by the aperture of the acousto-optic modulator 7, which increases the number of channels while maintaining modulation efficiency, enabling multiple lasers to be output synchronously. Compared with four independent modulators, the synchronous output consistency is higher, the cost is reduced by about 60-70%, and the size is significantly reduced.

[0032] In some embodiments, the distance L between the first position and the second position is less than 80% of the aperture of the acousto-optic modulator. This ensures that both beams are within the effective modulation region of the acousto-optic modulator, avoiding modulation efficiency reduction or waveform distortion caused by edge effects, and guaranteeing the modulation consistency of the four laser beams.

[0033] In some embodiments, the distance L between the first position and the second position is 15mm-16mm. For example, using an acousto-optic modulator 7 with a large aperture can achieve time-synchronized pulsed CO2 laser output with more wavelengths. Since the seed light spot diameter is 3-4mm, the aperture of the acousto-optic modulator 7 is larger. While considering both the aperture and spot size of the acousto-optic modulator 7, the value of L is maximized. For example, with an aperture of 20mm for the acousto-optic modulator 7, the incident point is located at both ends of the aperture, and the maximum value of L can reach 16mm. After modulation and output, there is sufficient space to guide the light into the output mirror using a catadioptric mirror. If an acousto-optic modulator 7 with an even larger aperture is used, time-synchronized pulsed laser output with more wavelengths can also be achieved according to this scheme.

[0034] In some embodiments, the blazed grating and / or the beam combiner grating have a diffraction efficiency >90% in the 9μm~11μm wavelength range. High diffraction efficiency reduces intracavity loss, increases laser output power (approximately 25% higher than a grating with 80% efficiency), reduces thermal load, and improves beam quality and long-term stability.

[0035] In some embodiments, the incident angle of the beam combiner grating corresponding to the 10.57μm band is: The incident angle of the beam combiner grating corresponding to the 10.59μm band is The diffraction angle of the beam combiner grating is 31.94°. Precise angle design enables coaxial beam combining of two wavelengths with an emission angle deviation of <0.1mrad. The diffraction angle of 31.94° is the average angle of the two wavelengths, ensuring that the two beams completely overlap in space after beam combining, which facilitates the subsequent design of a common aperture transmitting / receiving optical system.

[0036] In some embodiments, the laser wavelengths are any four groups of CO2 laser spectral lines within the range of 9μm-11μm. For example, the wavelengths of the four lasers are 10.57μm, 10.59μm, 10.61μm, and 10.63μm. Due to the small wavelength spacing, it is usually difficult to separate and maintain synchronous output in a conventional structure. This laser device can achieve synchronous output of multiple pulsed lasers under the action of an acousto-optic modulator 7.

[0037] According to a specific embodiment of this application, this application also provides a method for time-synchronized multi-wavelength pulsed CO2 laser output, which includes the following steps: S1: Select multiple sets of incident light of set wavelengths in CO2 laser for reflection and amplification; for example, select CO2 lasers with wavelengths of 10.57μm and 10.59μm, filter lasers of other wavelengths through the first blazed grating 1 and the second blazed grating 2, and amplify them by the first laser gain tube 3 and the second laser gain tube 4. S2: The laser after gain is configured as a multi-wavelength laser to satisfy the Bragg condition. After passing through the first folding mirror 5 and the second folding mirror 6, it is incident on the acousto-optic modulator 7 and output as a multi-wavelength time-synchronized pulsed laser. S3: After passing through the first output mirror 10 and the second output mirror 9, part of the pulsed laser is reflected back to the first blazed grating 1 and the second blazed grating 2 for further amplification, and part is transmitted to the beam combiner grating 14 to continuously output a time-synchronized multi-wavelength pulsed laser at the same exit angle.

[0038] In some embodiments, the time-synchronized multi-wavelength laser, after passing through the first output mirror 10 and the second output mirror 9, is partially reflected back to the first blazed grating 1 and the second blazed grating 2 for further amplification, and partially transmitted to the beam combiner grating 14, continuously outputting time-synchronized multi-wavelength pulsed laser at the same exit angle. This includes: such as... Figure 3 As shown, the time-synchronized multi-wavelength laser is first combined by the beam combiner grating 14, and then continuously output to a set of output mirrors at the same exit angle. Part of it is reflected back to the first blazed grating 1 and the second blazed grating 2 for further amplification, and part of it is continuously output as a time-synchronized multi-wavelength pulsed laser.

[0039] In some embodiments, the time-synchronized multi-wavelength laser, after being partially reflected by the first output mirror 10 and the second output mirror 9, is further amplified by the first blazed grating 1 and the second blazed grating 2, and partially transmitted to the beam combiner grating 14, continuously outputting multi-time-synchronized multi-wavelength pulsed laser at the same exit angle, includes: as follows Figure 1 As shown, the time-synchronized multi-wavelength laser first passes through the first output mirror 10 and the second output mirror 9, and then part of it is reflected back to the first blazed grating 1 and the second blazed grating 2 for further amplification. Part of it is transmitted to the beam combiner grating 14, and then the time-synchronized multi-wavelength pulsed laser is continuously output at the same exit angle.

[0040] 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.

[0041] 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 time-synchronized multi-wavelength pulsed laser output device, characterized in that, include: The multi-group beam splitting gain module includes a blazed grating and a laser gain tube in each group. Each blazed grating is configured to reflect incident light of a set wavelength into the laser gain tube. Each group of beam splitting gain modules is used to generate lasers of different wavelengths, and the set difference between the wavelengths of the lasers is less than 0.02 μm. An acousto-optic modulator is configured such that multiple groups of multi-wavelength lasers with enhanced gain are incident on the acousto-optic modulator to satisfy the Bragg condition, and the timing of each pulse laser is synchronized. At least two groups of lasers are incident on the same position of the acousto-optic modulator. One or more sets of output mirrors, each set of output mirrors is coated with a semi-transparent and semi-reflective film, and each set of output mirrors forms a resonant cavity with a set of blazed gratings. The laser of the set wavelength is returned to the laser gain tube through the output mirrors and resonates with the blazed gratings, and part of it is transmitted through the output mirrors. A beam combiner grating combines pulsed lasers of different wavelengths and outputs them at the same exit angle.

2. The apparatus according to claim 1, characterized in that, The beam combining grating is located outside the resonant cavity. Pulsed lasers of different wavelengths are output from the output mirror and then incident on the beam combining grating for beam combining.

3. The apparatus according to claim 1, characterized in that, The beam combining grating is located inside the resonant cavity. Pulsed lasers of different wavelengths are incident on the beam combining grating and then output from the output mirror.

4. The apparatus according to claim 1, characterized in that, Each laser wavelength includes CO2 laser spectral lines in the range of 9μm-11μm.

5. The apparatus according to claim 1, characterized in that, The multi-component optical gain module consists of four groups, of which two groups of lasers satisfy the Bragg condition and are incident on the first position of the acousto-optic modulator, and the other two groups of lasers satisfy the Bragg condition and are incident on the second position of the acousto-optic modulator, respectively. The distance between the first position and the second position is L.

6. The apparatus according to claim 5, characterized in that, The distance L between the first position and the second position is less than 80% of the aperture of the acousto-optic modulator.

7. The apparatus according to claim 5, characterized in that, The distance d between the first position and the second position is 15mm-16mm.

8. The apparatus according to claim 1, characterized in that, The blazed grating and / or the beam combiner grating have a diffraction efficiency of >90% in the 9μm~11μm band.

9. The apparatus according to claim 4, characterized in that, The laser wavelengths are 10.57 μm and 10.59 μm, and the incident angle of the beam combining grating corresponding to the 10.57 μm spectral line is... The incident angle of the beam combiner grating corresponding to the 10.59 μm spectral line is The diffraction angle of the beam combiner grating is 31.94°; the incident angle of the blazed grating corresponding to the 10.57μm band is 31.90°, and the incident angle of the blazed grating corresponding to the 10.59μm band is 31.97°.

10. The apparatus according to claim 5, characterized in that, The laser wavelengths are any four sets of CO2 laser spectral lines within the range of 9μm-11μm.

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