Laser and method of generating laser light

Abstract

This application provides a laser and a method for generating laser light. The laser includes: a laser seed source for providing a first pulse; a first amplifier for amplifying the energy of the first pulse to obtain a second pulse; a frequency multiplier for amplifying the frequency of the second pulse to obtain a third pulse; and a second amplifier, the second amplifier including a crystal, for amplifying the energy of the third pulse to obtain a fourth pulse. The laser provided by this application can achieve high-energy pulse output.

Description

Technical Field

[0001] This application relates to the field of optical technology, specifically to a laser and a method for generating laser light. Background Technology

[0002] High-energy, short-duration pulsed lasers, with their advantages in material processing, laser cutting, precision machining, and processing of hard and brittle materials, are gradually becoming an important requirement for advanced manufacturing in the future.

[0003] Common pulsed lasers mainly amplify pulse energy through fiber amplifiers, but the energy of the output pulse is limited by the accumulation of nonlinearity in the fiber. Summary of the Invention

[0004] This application provides a laser and a method for generating laser light, which can achieve high-energy pulse output.

[0005] In a first aspect, a laser is provided, comprising: a laser seed source for providing a first pulse; a first amplifier for amplifying the energy of the first pulse to obtain a second pulse; a frequency multiplier for amplifying the frequency of the second pulse to obtain a third pulse; and a second amplifier, the second amplifier including a crystal, for amplifying the energy of the third pulse to obtain a fourth pulse.

[0006] The center wavelength of the first pulse provided by the laser seed source is typically in the range of 1500nm to 1620nm, making direct energy amplification using a crystal impossible. This application provides a laser comprising a laser seed source, a first amplifier, a frequency doubler, and a second amplifier. By introducing a frequency doubler before the second amplifier, the wavelength of the pulse can be shortened, allowing the energy of the pulse to be further amplified using a crystal. This crystal-based pulse energy amplification reduces the nonlinear effects of the pulsed laser in the gain medium, thereby obtaining a high-power, high-energy pulsed laser.

[0007] In conjunction with the first aspect, in some implementations of the first aspect, the crystal includes emerald, sapphire, or ruby.

[0008] The crystal can be an all-solid-state crystal. The third pulse is absorbed, excited, and amplified in emerald, sapphire, or ruby, which can generate high-energy pulsed laser.

[0009] This application provides a laser that uses emerald, sapphire, or ruby ​​as an amplifier to reduce the nonlinear effect of pulsed laser in the gain medium, thereby obtaining a high-power, high-energy pulsed laser.

[0010] In conjunction with the first aspect, in some implementations of the first aspect, the laser further includes a pulse stretcher for amplifying the width of the first pulse in the time domain.

[0011] In lasers, excessively high pulse peak power can enhance nonlinear optical effects, such as self-focusing and self-phase modulation, which may affect the performance and stability of the laser system. The laser provided in this application includes a pulse stretcher after the laser seed source, which can lengthen the input first pulse in the time domain, reduce the peak power of the first pulse, avoid damage to optical components in the laser, and improve the stability of the laser system.

[0012] In conjunction with the first aspect, in some implementations of the first aspect, the pulse stretcher includes any one or more of the following: single-mode fiber, chirped fiber bragg grating (CFBG), and diffraction grating.

[0013] The laser provided in this application does not limit the number of pulse stretchers used. One pulse stretcher can be used to amplify the pulse width in the time domain, or multiple pulse stretchers can be used to amplify the pulse width in the time domain.

[0014] Chirped fiber gratings can simultaneously fine-tune second-order and third-order dispersion for use in ultrashort pulse scenarios, which can improve the integration of lasers, reduce the complexity of laser systems, and improve the reliability of laser systems.

[0015] In conjunction with the first aspect, in some implementations of the first aspect, the laser further includes a compressor for reducing the width of the second pulse in the time domain or reducing the width of the fourth pulse in the time domain.

[0016] In some potential applications, lasers incorporate pulse stretchers to amplify the pulse width in the time domain, and compressors can be used to recompress the pulse to help restore its short-time characteristics.

[0017] In other potential applications, it is necessary to transmit short pulses with high peak power to improve transmission efficiency. In such cases, compressors can help maintain the short time-domain characteristics of the pulses to ensure efficient data transmission.

[0018] The compressor can be placed after the first amplifier to reduce the width of the second pulse in the time domain, or the compressor can be placed after the second amplifier to reduce the width of the fourth pulse in the time domain.

[0019] In conjunction with the first aspect, in some implementations of the first aspect, the compressor includes a diffraction grating pair, an optical fiber delayer, a grating-prism compressor, or an optical fiber dispersion compensator.

[0020] For example, the diffraction grating compressor can further compress the width of high-energy pulses. Combined with the second-order and third-order dispersion matching design at the front end, it can achieve picosecond or femtosecond ultrashort high-energy pulse output, so that the output pulse has high peak power.

[0021] In conjunction with the first aspect, in some implementations of the first aspect, the frequency multiplier includes periodically poled lithium niobate (PPLN), periodically poled magnesium oxide-doped lithium niobate (MgO:PPLN), beta barium borate (BBO), bismuth borate (BIBO), potassium titanyl phosphate (KTP), lithium triborate (LBO), photonics crystal fiber (PCF), or high nonlinear fiber (HNLF).

[0022] A frequency multiplier is a device used to double the frequency of an optical signal (i.e., to multiply the frequency). Since the speed of light = wavelength × frequency, when the frequency is doubled, the wavelength is halved. For example, this frequency multiplier can make the frequency of a second pulse two, three, or four times the original frequency, and the wavelength of the second pulse will become one-half, one-third, or one-quarter of the original wavelength. This application does not limit the specific multiplication value.

[0023] This application provides a laser in which the wavelength of the pulse can be shortened by introducing a frequency multiplier before the second amplifier, thereby allowing the energy of the pulse to be further amplified by a crystal. The way the crystal amplifies the pulse energy can reduce the nonlinear effect of the pulsed laser in the gain medium, thereby obtaining a high-power, high-energy pulsed laser.

[0024] In conjunction with the first aspect, in some implementations of the first aspect, the laser seed source includes a femtosecond mode-locked laser seed source or a picosecond mode-locked laser seed source.

[0025] When the laser seed source is a femtosecond mode-locked laser seed source, the laser seed source can provide femtosecond-level pulses; when the laser seed source is a picosecond mode-locked laser seed source, the laser seed source can provide picosecond-level pulses.

[0026] The laser seed source can be a semiconductor saturable absorber mirror (SESAM) or a nonlinear amplifying loop mirror (NALM) mode-locking method.

[0027] In conjunction with the first aspect, in some implementations of the first aspect, the first amplifier includes any one or more of the following: single-mode fiber, double-clad fiber.

[0028] In some possible application scenarios, the first amplifier includes both single-mode fiber and double-clad fiber. The first pulse can first pass through the single-mode fiber to amplify its energy, and then pass through the double-clad fiber to further amplify its energy to obtain the second pulse.

[0029] In some other possible application scenarios, the first amplifier includes multiple single-mode optical fibers. The first pulse can first pass through a portion of the single-mode optical fibers to amplify its energy, and then pass through another portion of the single-mode optical fibers to further amplify its energy to obtain the second pulse.

[0030] In some other possible application scenarios, the first amplifier includes multiple double-clad optical fibers. The first pulse can first pass through a portion of the double-clad optical fibers to amplify its energy, and then pass through another portion of the double-clad optical fibers to further amplify its energy, thus obtaining the second pulse.

[0031] In conjunction with the first aspect, in some implementations of the first aspect, the center wavelength range of the fourth pulse is 750 nm to 810 nm.

[0032] In conjunction with the first aspect, in some implementations of the first aspect, the center wavelength range of the first pulse is 1500nm to 1620nm.

[0033] In conjunction with the first aspect, in some implementations of the first aspect, the energy range of the second pulse is 0.1 μJ to 10 μJ.

[0034] In conjunction with the first aspect, in some implementations of the first aspect, the energy range of the fourth pulse is 10 μJ to 1000 μJ.

[0035] In a second aspect, a method for generating laser light is provided, comprising: a laser seed source in a laser providing a first pulse; a first amplifier in the laser amplifying the energy of the first pulse to obtain a second pulse; a frequency multiplier in the laser amplifying the frequency of the second pulse to obtain a third pulse; and a second amplifier in the laser amplifying the energy of the third pulse to obtain a fourth pulse, wherein the second amplifier includes a crystal.

[0036] The center wavelength of the first pulse provided by the laser seed source is typically in the range of 1500nm to 1620nm, making direct energy amplification using a crystal impossible. This application provides a method for using a laser by introducing a frequency doubler before the second amplifier to shorten the pulse wavelength, thereby enabling further energy amplification of the pulse using a crystal. This crystal-based pulse energy amplification reduces the nonlinear effects of the pulsed laser in the gain medium, resulting in a high-power, high-energy pulsed laser. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the structure of a laser provided in an embodiment of this application.

[0038] Figure 2 This is a schematic diagram of the specific structure of a laser 100 provided in an embodiment of this application.

[0039] Figure 3 This is a schematic diagram of another laser structure provided in an embodiment of this application.

[0040] Figure 4 This is a schematic diagram of the specific structure of a laser 200 provided in an embodiment of this application.

[0041] Figure 5 This is a schematic diagram of the specific structure of another laser 200 provided in the embodiments of this application.

[0042] Figure 6 This is a schematic diagram of another laser structure provided in an embodiment of this application.

[0043] Figure 7 This is a schematic diagram of the specific structure of a laser 300 provided in an embodiment of this application.

[0044] Figure 8 This is a schematic diagram of another laser structure provided in an embodiment of this application.

[0045] Figure 9 This is a schematic diagram of the specific structure of a laser 400 provided in an embodiment of this application.

[0046] Figure 10 This is a schematic diagram of another laser structure provided in an embodiment of this application.

[0047] Figure 11 This is a schematic diagram of the specific structure of a laser 500 provided in an embodiment of this application. Detailed Implementation

[0048] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort should fall within the scope of protection of this application.

[0049] In the embodiments of this application, the words "exemplary," "for example," etc., are used to indicate that they are examples, illustrations, or descriptions. Any embodiment or design that is described as "exemplary" in this application should not be construed as being more preferred or advantageous than other embodiments or design options. Specifically, the use of the term "exemplary" is intended to present the concept in a concrete manner.

[0050] The business scenarios described in the embodiments of this application are for the purpose of more clearly illustrating the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided in the embodiments of this application. As those skilled in the art will know, with the emergence of new business scenarios, the technical solutions provided in the embodiments of this application are also applicable to similar technical problems.

[0051] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0052] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0053] In this application, "at least one" means one or more, and "more than one" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A alone, A and B simultaneously, and B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can mean: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or multiple.

[0054] To facilitate understanding of the embodiments of this application, some definitions involved in this application will be briefly explained first.

[0055] 1. Mode-locking effect: This refers to the phenomenon that when the input light intensity just meets certain conditions, the oscillation mode of the laser will be locked on a specific mode, thereby realizing the output pulsed laser.

[0056] 2. Center wavelength: refers to the main wavelength of laser output, which is usually the emission wavelength of the laser under normal operating conditions.

[0057] 3. Semiconductor saturable absorber mirror (SESAM): A device used for mode-locking lasers, typically for generating ultrashort pulse lasers. The SESAM structure comprises semiconductor materials and thin-film lenses, exhibiting nonlinear optical absorption characteristics. It can introduce a saturable absorption effect within the laser cavity, thereby achieving pulse mode-locking.

[0058] 4. Nonlinear amplifying loop mirror (NALM): A device used for mode-locking in lasers, commonly used to generate ultrashort pulse lasers. NALM utilizes the nonlinear effects in optical fibers to achieve laser mode-locking within a loop fiber structure.

[0059] 5. Pulse stretcher: A device used to extend the width of a laser pulse. It is commonly used in ultrashort pulse laser systems. Its function is to lengthen the original short pulse in the time domain for subsequent processing or applications.

[0060] 6. Frequency doubling: This refers to the process of doubling the frequency of a pulse to generate a new pulse with a multiple of its frequency. This process is usually achieved through nonlinear optical effects.

[0061] 7. Chirped Fiber Bragg Grating (CFBG): A type of fiber grating with a periodic refractive index variation. Unlike ordinary Bragg gratings, the refractive index variation of a chirped fiber Bragg grating is non-uniform, meaning the refractive index changes with the fiber length, resulting in dispersion. Due to the non-uniformity of the chirped fiber Bragg grating, its dispersion characteristics also change. The amount of dispersion in a chirped fiber Bragg grating can be controlled by adjusting the chirp rate, and changes in the chirp rate directly affect the dispersion characteristics of the fiber.

[0062] 8. Pulse wavelength describes the wavelength characteristics of a pulse signal in space, that is, the wavelength range of the pulse signal in the spectrum, which is the spatial domain characteristic of the pulse signal. Pulse width describes the duration of the pulse signal in time, which is the temporal domain characteristic of the pulse signal.

[0063] High-energy, short-duration pulsed lasers, with their advantages in material processing, laser cutting, precision machining, and processing of hard and brittle materials, are gradually becoming an important requirement for advanced manufacturing in the future.

[0064] The generation mechanism of pulsed lasers is based on the mode-locking effect of mode-locking elements to achieve the coherent temporal superposition of different longitudinal modes. Types of mode-locking elements mainly include saturable absorbers, nonlinear polarization rotation elements, NALMs, active Q-switching elements, and passive Q-switching elements. Saturable absorbers utilize the nonlinear absorption characteristic under high light intensity to achieve pulse mode-locking and generation, enabling lasers to generate ultrashort pulses. Nonlinear polarization rotation elements utilize nonlinear optical effects to achieve mode-locking by adjusting the polarization state of light, and are commonly used to generate femtosecond laser pulses. NALMs are nonlinear optical elements that achieve mode locking and generate ultrashort pulses through nonlinear effects. Active Q-switching elements use active modulation devices (such as electro-optic modulators) to control the Q value of the laser, thereby achieving mode-locking. Passive Q-switching elements use nonlinear elements (such as saturable absorbers) to control the Q value of the laser to generate mode-locked pulses; unlike active Q-switching, they do not require external intervention.

[0065] Common pulsed lasers mainly include all-fiber lasers, fiber-plus-solid-state amplified lasers, all-solid-state lasers, and on-chip lasers. The generation methods for pulsed lasers of different wavelengths mainly include direct generation via gain media, nonlinear frequency conversion, Raman shifting, and optical parametric amplification. Common pulsed lasers primarily amplify pulse energy using fiber amplifiers; however, the energy of the output pulse is limited by the accumulation of nonlinearity in the fiber.

[0066] This application provides a laser that can reduce pulse energy limitations and achieve high-energy pulse output.

[0067] Figure 1 This is a schematic diagram of the structure of a laser provided in an embodiment of this application.

[0068] The laser 100 includes a laser seed source 110, a first amplifier 120, a frequency multiplier 130, and a second amplifier 140.

[0069] The laser seed source 110 is used to provide the first pulse. The center wavelength range of the first pulse can be 1500nm to 1620nm. The laser seed source 110 can adopt an all-fiber SESAM or NALM mode-locking method.

[0070] The laser seed source 110 includes either a femtosecond mode-locked laser seed source or a picosecond mode-locked laser seed source. When the laser seed source 110 is a femtosecond mode-locked laser seed source, it can provide femtosecond-level pulses; when the laser seed source 110 is a picosecond mode-locked laser seed source, it can provide picosecond-level pulses.

[0071] The first amplifier 120 is used to amplify the energy of the first pulse to obtain the second pulse. The energy range of the second pulse can be 0.1 μJ to 10 μJ.

[0072] For example, the first amplifier 120 may include any one or more of the following: single-mode fiber and double-clad fiber. In some possible application scenarios, the first amplifier 120 includes both single-mode fiber and double-clad fiber. The first pulse can be amplified by passing through the single-mode fiber first, and then further amplified by passing through the double-clad fiber to obtain the second pulse. In other possible application scenarios, the first amplifier 120 includes multiple single-mode fibers. The first pulse can be amplified by passing through some single-mode fibers first, and then further amplified by passing through another portion of single-mode fibers to obtain the second pulse. In still other possible application scenarios, the first amplifier 120 includes multiple double-clad fibers. The first pulse can be amplified by passing through some double-clad fibers first, and then further amplified by passing through another portion of double-clad fibers to obtain the second pulse.

[0073] Frequency multiplier 130 is used to amplify the frequency of the second pulse to obtain the third pulse. Frequency multiplier 130 is a device used to double the frequency of an optical signal (i.e., perform frequency multiplication). Since the speed of light = wavelength × frequency, when the frequency is doubled, the wavelength is halved. For example, frequency multiplier 130 can double, triple, or quadruple the frequency of the second pulse, and the wavelength of the second pulse will correspondingly become half, one-third, or one-quarter of its original value. This application does not limit the specific multiplication value. Frequency multiplier 130 includes, but is not limited to, PPLN, MgO:PPLN, BBO, BIBO, KTP, LBO, PCF, or HNLF.

[0074] The second amplifier 140 amplifies the energy of the third pulse to obtain a fourth pulse. The second amplifier 140 includes a crystal. The center wavelength range of the fourth pulse can be 750 nm to 810 nm, and the energy range of the fourth pulse can be 10 μJ to 1000 μJ. The crystal includes emerald green, sapphire, or ruby. Using emerald green, sapphire, or ruby ​​as an amplifier can reduce the nonlinear effects of the pulsed laser in the gain medium, thereby obtaining a high-power, high-energy pulsed laser.

[0075] Figure 2 This is a schematic diagram of the specific structure of a laser 100 provided in an embodiment of this application.

[0076] The first pulse provided by the laser seed source 110 is a femtosecond or picosecond pulse with a center wavelength around 1560nm. It can be a full-fiber SESAM or NALM mode-locked pulse, and its spectral characteristics can be narrow or wide (≥5nm).

[0077] The first amplifier 120 includes a single-mode pump, a single-mode fiber, a multi-mode pump, and a double-clad fiber. The first pulse is first amplified by the single-mode pump and the single-mode fiber, and then further amplified by the multi-mode pump and the double-clad fiber to obtain the second pulse. The energy range of the second pulse can be 0.1 μJ to 10 μJ.

[0078] The frequency multiplier 130 can select frequency doubling crystals including, but not limited to, PPLN, MgO:PPLN, BBO, BIBO, KTP, LBO, PCF, or HNLF. For example, the frequency multiplier 130 doubles the frequency of the second pulse, thereby halving the wavelength, resulting in a third pulse with a wavelength around 780 nm.

[0079] The second amplifier 140 may include emerald green. The third pulse, after being pumped by visible light and passed through the emerald green, is absorbed, excited, and amplified in the emerald green, generating a fourth pulse with an average power greater than 10W, a pulse energy greater than 100uJ, and a center wavelength around 780nm. The visible light pump can be a high-brightness light source in the 600nm band, such as a laser diode.

[0080] The laser 100 provided in this application embodiment introduces a frequency multiplier 130 before the second amplifier 140, which can shorten the wavelength of the pulse, thereby using alexandrite to further amplify the energy of the pulse. The way alexandrite amplifies the pulse energy can reduce the nonlinear effect of the pulsed laser in the gain medium, thereby obtaining a high-power, high-energy pulsed laser.

[0081] Figure 3 This is a schematic diagram of another laser structure provided in an embodiment of this application.

[0082] The laser 200 includes a laser seed source 210, a pulse stretcher 215, a first amplifier 220, a frequency multiplier 230, and a second amplifier 240.

[0083] The laser seed source 210 is used to provide the first pulse 1. The center wavelength range of the first pulse 1 can be 1500nm to 1620nm. The laser seed source 210 can adopt an all-fiber SESAM or NALM mode-locking method.

[0084] The laser seed source 210 includes either a femtosecond mode-locked laser seed source or a picosecond mode-locked laser seed source. When the laser seed source 210 is a femtosecond mode-locked laser seed source, it can provide femtosecond-level pulses; when it is a picosecond mode-locked laser seed source, it can provide picosecond-level pulses.

[0085] Pulse stretcher 215 is used to amplify the width of the first pulse 1 in the time domain. Pulse stretcher 215 includes any one or more of the following: single-mode fiber, CFBG, and diffraction grating. For applications with high integration and multiple wavelengths of different pulse widths, large-range active tuning of the pulse width can be achieved by controlling the dispersion of the CFBG or the spacing of the diffraction grating pairs. In laser 200, excessively high pulse peak power may cause enhancement of nonlinear optical effects, such as self-focusing and self-phase modulation, which may affect the performance and stability of the laser system. This application sets pulse stretcher 215 after the laser seed source 210, which can lengthen the input first pulse 1 in the time domain, reduce the peak power of the first pulse 1, avoid damage to optical components in laser 200, and improve the stability of the laser system.

[0086] The first amplifier 220 is used to amplify the energy of the first pulse 2 to obtain the second pulse. The energy range of the second pulse can be 0.1μJ to 10μJ.

[0087] For example, the first amplifier 220 may include any one or more of the following: single-mode fiber and double-clad fiber. In some possible application scenarios, the first amplifier 220 includes both single-mode fiber and double-clad fiber. The first pulse 2 can first pass through the single-mode fiber to amplify its energy, and then pass through the double-clad fiber for further amplification to obtain the second pulse. In other possible application scenarios, the first amplifier 220 includes multiple single-mode fibers. The first pulse 2 can first pass through some of the single-mode fibers to amplify its energy, and then pass through another portion of the single-mode fibers for further amplification to obtain the second pulse. In other possible application scenarios, the first amplifier 220 includes multiple double-clad fibers. The first pulse 2 can first pass through some of the double-clad fibers to amplify its energy, and then pass through another portion of the double-clad fibers for further amplification to obtain the second pulse.

[0088] Frequency multiplier 230 is used to amplify the frequency of the second pulse to obtain the third pulse. Frequency multiplier 230 is a device used to double the frequency of an optical signal (i.e., perform frequency multiplication). Since the speed of light = wavelength × frequency, when the frequency is doubled, the wavelength is halved. For example, frequency multiplier 230 can double, triple, or quadruple the frequency of the second pulse, and the wavelength of the second pulse will correspondingly become half, one-third, or one-quarter of its original value. This application does not limit the specific multiplication value. Frequency multiplier 230 includes, but is not limited to, PPLN, MgO:PPLN, BBO, BIBO, KTP, LBO, PCF, or HNLF.

[0089] The second amplifier 240 amplifies the energy of the third pulse to obtain a fourth pulse. The second amplifier 240 includes a crystal. The center wavelength range of the fourth pulse can be 750 nm to 810 nm, and the energy range of the fourth pulse can be 10 μJ to 1000 μJ. The crystal includes emerald green, sapphire, or ruby. Using emerald green, sapphire, or ruby ​​as an amplifier can reduce the nonlinear effects of the pulsed laser in the gain medium, thereby obtaining a high-power, high-energy pulsed laser.

[0090] Figure 4 This is a schematic diagram of the specific structure of a laser 200 provided in an embodiment of this application.

[0091] The first pulse 1 provided by the laser seed source 210 is a femtosecond or picosecond pulse with a center wavelength around 1560nm. It can be a SESAM or NALM mode-locked pulse with all-fiber optics, and its spectral characteristics can be narrow or wide (≥5nm).

[0092] The pulse stretcher 215 includes a pulse stretching fiber, which may be a section of highly nonlinear fiber. The pulse stretching fiber receives a first pulse 1 and amplifies its width in the time domain to obtain a first pulse 2.

[0093] The first amplifier 220 includes a single-mode pump, a single-mode fiber, a multi-mode pump, and a double-clad fiber. The first pulse 2 is first amplified by the single-mode pump and the single-mode fiber, and then further amplified by the multi-mode pump and the double-clad fiber to obtain the second pulse. The energy range of the second pulse can be 0.1 μJ to 10 μJ.

[0094] The frequency multiplier 230 can select frequency doubling crystals including, but not limited to, PPLN, MgO:PPLN, BBO, BIBO, KTP, LBO, PCF, or HNLF. For example, the frequency multiplier 230 doubles the frequency of the second pulse, thereby halving the wavelength, resulting in a third pulse with a wavelength around 780 nm.

[0095] The second amplifier 240 may include emerald green. The third pulse, after being pumped by visible light and passed through the emerald green, is absorbed, excited, and amplified in the emerald green, generating a fourth pulse with an average power greater than 10W, a pulse energy greater than 100uJ, and a center wavelength around 780nm. The visible light pump can be a high-brightness light source in the 600nm band, such as a laser diode.

[0096] The laser 200 provided in this application embodiment introduces a frequency multiplier 230 before the second amplifier 240, which can shorten the wavelength of the pulse, thereby using alexandrite to further amplify the energy of the pulse. The way alexandrite amplifies the pulse energy can reduce the nonlinear effect of the pulsed laser in the gain medium, thereby obtaining a high-power, high-energy pulsed laser.

[0097] Meanwhile, the pulse stretcher 215 of the laser 200 employs a section of highly nonlinear fiber. By adjusting the length of the highly nonlinear single-mode fiber, the pulse stretching width can be controlled. Since highly nonlinear single-mode fibers generally have large dispersion, the laser 200 can achieve large-range active tuning of the pulse width, which simplifies the complexity of the laser and reduces cost and power consumption.

[0098] In the laser 200 provided in this application embodiment, the pulse energy is increased by an all-solid-state crystal after the frequency doubler 230. This can ensure high-quality beam output while improving the integration of the laser. At the same time, the laser as a whole has low nonlinearity, and the upper limit of the pulse energy mainly depends on the visible pump light. The laser has high stability.

[0099] Figure 5 This is a schematic diagram of the specific structure of another laser 200 provided in the embodiments of this application.

[0100] The first pulse 1 provided by the laser seed source 210 is a femtosecond or picosecond pulse with a center wavelength around 1560nm. It can be a SESAM or NALM mode-locked pulse with all-fiber optics, and its spectral characteristics can be narrow or wide (≥5nm).

[0101] The pulse stretcher 215 includes a CFBG, which can simultaneously fine-tune the second and third order dispersions for application in ultrashort pulse scenarios. The CFBG receives the first pulse 1 and amplifies its width in the time domain to obtain the first pulse 2.

[0102] The first amplifier 220 includes a single-mode pump, a single-mode fiber, a multi-mode pump, and a double-clad fiber. The first pulse 2 is first amplified by the single-mode pump and the single-mode fiber, and then further amplified by the multi-mode pump and the double-clad fiber to obtain the second pulse. The energy range of the second pulse can be 0.1 μJ to 10 μJ.

[0103] The frequency multiplier 230 can select frequency doubling crystals including, but not limited to, PPLN, MgO:PPLN, BBO, BIBO, KTP, LBO, PCF, or HNLF. For example, the frequency multiplier 230 doubles the frequency of the second pulse, thereby halving the wavelength, resulting in a third pulse with a wavelength around 780 nm.

[0104] The second amplifier 240 may include emerald green. The third pulse, after being pumped by visible light and passed through the emerald green, is absorbed, excited, and amplified in the emerald green, generating a fourth pulse with an average power greater than 10W, a pulse energy greater than 100uJ, and a center wavelength around 780nm. The visible light pump can be a high-brightness light source in the 600nm band, such as a laser diode.

[0105] The laser 200 provided in this application embodiment introduces a frequency multiplier 230 before the second amplifier 240, which can shorten the wavelength of the pulse, thereby using alexandrite to further amplify the energy of the pulse. The way alexandrite amplifies the pulse energy can reduce the nonlinear effect of the pulsed laser in the gain medium, thereby obtaining a high-power, high-energy pulsed laser.

[0106] Meanwhile, the pulse stretcher 215 of the laser 200 adopts CFBG, which can simultaneously fine-tune the second-order and third-order dispersion for application in ultrashort pulse scenarios, improving the integration and reliability of the laser and reducing the complexity of the laser.

[0107] In the laser 200 provided in this application embodiment, the pulse energy is increased by using an all-solid-state crystal after the frequency multiplier 230. This can ensure high-quality beam output while improving the integration of the laser. At the same time, the CFBG can simultaneously fine-tune the second-order and third-order dispersion for application in ultrashort pulse scenarios, so as to achieve large-range active tuning of high-power pulse width. This can simplify the complexity of the laser and reduce cost and power consumption.

[0108] Figure 6 This is a schematic diagram of another laser structure provided in an embodiment of this application.

[0109] The laser 300 includes a laser seed source 310, a pulse stretcher 315, a first amplifier 320, a frequency multiplier 330, a second amplifier 340, and a compressor 350.

[0110] The laser seed source 310 is used to provide the first pulse 1. The center wavelength range of the first pulse 1 can be 1500nm to 1620nm. The laser seed source 310 can adopt an all-fiber SESAM or NALM mode-locking method.

[0111] The laser seed source 310 includes either a femtosecond mode-locked laser seed source or a picosecond mode-locked laser seed source. When the laser seed source 310 is a femtosecond mode-locked laser seed source, it can provide femtosecond-level pulses; when the laser seed source 310 is a picosecond mode-locked laser seed source, it can provide picosecond-level pulses.

[0112] The pulse stretcher 315 is used to amplify the width of the first pulse 1 in the time domain. The pulse stretcher 315 includes any one or more of the following: single-mode fiber, CFBG, and diffraction grating. For applications with different pulse widths and high integration across multiple wavelengths, large-range active tuning of the pulse width can be achieved by controlling the dispersion of the CFBG or the spacing of the diffraction grating pairs. In the laser 300, excessively high pulse peak power may cause enhancement of nonlinear optical effects, such as self-focusing and self-phase modulation, which may affect the performance and stability of the laser system. This application allows the pulse stretcher 315 to be placed after the laser seed source 310, which can lengthen the input first pulse 1 in the time domain, reduce the peak power of the first pulse 1, avoid damage to the optical components in the laser 300, and improve the stability of the laser system.

[0113] The first amplifier 320 is used to amplify the energy of the first pulse 2 to obtain the second pulse. The energy range of the second pulse can be 0.1μJ to 10μJ.

[0114] For example, the first amplifier 320 may include any one or more of the following: single-mode fiber and double-clad fiber. In some possible application scenarios, the first amplifier 320 includes both single-mode fiber and double-clad fiber. The first pulse 2 can first pass through the single-mode fiber to amplify its energy, and then pass through the double-clad fiber for further amplification to obtain the second pulse. In other possible application scenarios, the first amplifier 320 includes multiple single-mode fibers. The first pulse 2 can first pass through some of the single-mode fibers to amplify its energy, and then pass through another portion of the single-mode fibers for further amplification to obtain the second pulse. In other possible application scenarios, the first amplifier 320 includes multiple double-clad fibers. The first pulse 2 can first pass through some of the double-clad fibers to amplify its energy, and then pass through another portion of the double-clad fibers for further amplification to obtain the second pulse.

[0115] Frequency multiplier 330 is used to amplify the frequency of the second pulse to obtain the third pulse. Frequency multiplier 330 is a device used to double the frequency of an optical signal (i.e., perform frequency multiplication). Since the speed of light = wavelength × frequency, when the frequency is doubled, the wavelength is halved. For example, frequency multiplier 330 can double, triple, or quadruple the frequency of the second pulse, and the wavelength of the second pulse will correspondingly become half, one-third, or one-quarter of its original value. This application does not limit the specific multiplication value. Frequency multiplier 330 includes, but is not limited to, PPLN, MgO:PPLN, BBO, BIBO, KTP, LBO, PCF, or HNLF.

[0116] The second amplifier 340 amplifies the energy of the third pulse to obtain a fourth pulse. The second amplifier 340 includes a crystal. The center wavelength range of the fourth pulse can be 750 nm to 810 nm, and the energy range of the fourth pulse can be 10 μJ to 1000 μJ. The crystal includes emerald green, sapphire, or ruby. Using emerald green, sapphire, or ruby ​​as an amplifier can reduce the nonlinear effects of the pulsed laser in the gain medium, thereby obtaining a high-power, high-energy pulsed laser.

[0117] Compressor 350 is used to reduce the width of the fourth pulse in the time domain. Compressor 350 includes, but is not limited to, diffraction grating pairs, fiber delay units, grating-prism compressors, or fiber dispersion compensators. Pulse stretcher 315 amplifies the pulse width in the time domain, and compressor 350 can recompress the pulse to help restore its short-time-domain characteristics.

[0118] Figure 7 This is a schematic diagram of the specific structure of a laser 300 provided in an embodiment of this application.

[0119] The first pulse 1 provided by the laser seed source 310 is a femtosecond or picosecond pulse with a center wavelength around 1560nm. It can be a SESAM or NALM mode-locked pulse with all-fiber optics, and its spectral characteristics can be narrow or wide (≥5nm).

[0120] The pulse stretcher 315 includes a pulse stretching fiber, which may be a section of highly nonlinear fiber. The pulse stretching fiber receives a first pulse 1 and amplifies its width in the time domain to obtain a first pulse 2.

[0121] The first amplifier 320 includes a single-mode pump, a single-mode fiber, a multi-mode pump, and a double-clad fiber. The first pulse 2 is first amplified by the single-mode pump and the single-mode fiber, and then further amplified by the multi-mode pump and the double-clad fiber to obtain the second pulse. The energy range of the second pulse can be 0.1 μJ to 10 μJ.

[0122] The frequency multiplier 330 can select frequency doubling crystals including, but not limited to, PPLN, MgO:PPLN, BBO, BIBO, KTP, LBO, PCF, or HNLF. For example, the frequency multiplier 330 doubles the frequency of the second pulse, thereby halving the wavelength, resulting in a third pulse with a wavelength around 780 nm.

[0123] The second amplifier 340 may include emerald green. The third pulse, after being pumped by visible light and passed through the emerald green, is absorbed, excited, and amplified in the emerald green, generating a fourth pulse with an average power greater than 10W, a pulse energy greater than 100uJ, and a center wavelength around 780nm. The visible light pump can be a high-brightness light source in the 600nm band, such as a laser diode.

[0124] Compressor 350 includes a pair of diffraction gratings for reducing the width of the fourth pulse in the time domain. Pulse stretcher 315 amplifies the pulse width in the time domain, and compressor 350 can recompress the pulse to help restore the short-time domain characteristics of the pulse.

[0125] The laser 300 provided in this application embodiment introduces a frequency multiplier 330 before the second amplifier 340, which can shorten the wavelength of the pulse, thereby using alexandrite to further amplify the energy of the pulse. The way alexandrite amplifies the pulse energy can reduce the nonlinear effect of the pulsed laser in the gain medium, thereby obtaining a high-power, high-energy pulsed laser.

[0126] Meanwhile, the pulse stretcher 315 of the laser 300 employs a section of highly nonlinear fiber. By adjusting the length of the highly nonlinear single-mode fiber, the pulse stretching width can be controlled. Since highly nonlinear single-mode fibers generally have large dispersion, the laser 300 can achieve large-range active tuning of the pulse width, which simplifies the complexity of the laser and reduces cost and power consumption.

[0127] In the laser 300 provided in this application embodiment, a diffraction grating pair is used as a large negative dispersion element, which can generate high-power pulses of picosecond and below. Combined with the second-order and third-order precise matching or control of the pulse stretcher 315, high-quality pulse output can be achieved.

[0128] Figure 8 This is a schematic diagram of another laser structure provided in an embodiment of this application.

[0129] The laser 400 includes a laser seed source 410, a pulse stretcher 415, a first amplifier 420, a compressor 450, a frequency multiplier 430, and a second amplifier 440.

[0130] The laser seed source 410 is used to provide the first pulse 1. The center wavelength range of the first pulse 1 can be 1500nm to 1620nm. The laser seed source 410 can adopt an all-fiber SESAM or NALM mode-locking method.

[0131] The laser seed source 410 includes either a femtosecond mode-locked laser seed source or a picosecond mode-locked laser seed source. When the laser seed source 410 is a femtosecond mode-locked laser seed source, it can provide femtosecond-level pulses; when the laser seed source 410 is a picosecond mode-locked laser seed source, it can provide picosecond-level pulses.

[0132] The pulse stretcher 415 is used to amplify the width of the first pulse 1 in the time domain. The pulse stretcher 415 includes any one or more of the following: single-mode fiber, CFBG, and diffraction grating. For applications with different pulse widths and high integration across multiple wavelengths, large-range active tuning of the pulse width can be achieved by controlling the dispersion of the CFBG or the spacing of the diffraction grating pairs. In the laser 400, excessively high pulse peak power may cause enhancement of nonlinear optical effects, such as self-focusing and self-phase modulation, which may affect the performance and stability of the laser system. This application allows the pulse stretcher 415 to be placed after the laser seed source 410, which can lengthen the input first pulse 1 in the time domain, reduce the peak power of the first pulse 1, avoid damage to the optical components in the laser 400, and improve the stability of the laser system.

[0133] The first amplifier 420 is used to amplify the energy of the first pulse 2 to obtain the second pulse 1. The energy range of the second pulse 1 can be 0.1μJ to 10μJ.

[0134] For example, the first amplifier 420 may include any one or more of the following: single-mode fiber and double-clad fiber. In some possible application scenarios, the first amplifier 420 includes both single-mode fiber and double-clad fiber. The first pulse 2 can first pass through the single-mode fiber to amplify its energy, and then pass through the double-clad fiber for further amplification to obtain the second pulse 1. In other possible application scenarios, the first amplifier 420 includes multiple single-mode fibers. The first pulse 2 can first pass through some of the single-mode fibers to amplify its energy, and then pass through another portion of the single-mode fibers for further amplification to obtain the second pulse 1. In other possible application scenarios, the first amplifier 420 includes multiple double-clad fibers. The first pulse 2 can first pass through some of the double-clad fibers to amplify its energy, and then pass through another portion of the double-clad fibers for further amplification to obtain the second pulse 1.

[0135] Compressor 450 is used to reduce the width of the second pulse 1 in the time domain to obtain the second pulse 2. This compressor 450 includes, but is not limited to, diffraction grating pairs, fiber delay units, grating-prism compressors, or fiber dispersion compensators. Pulse stretcher 415 amplifies the pulse width in the time domain, and compressor 450 can recompress the pulse to help restore its short-time-domain characteristics.

[0136] Frequency multiplier 430 is used to amplify the frequency of the second pulse 2 to obtain the third pulse. Frequency multiplier 430 is a device used to double the frequency of an optical signal (i.e., perform frequency multiplication). Since the speed of light = wavelength × frequency, when the frequency is doubled, the wavelength is halved. For example, frequency multiplier 430 can double, triple, or quadruple the frequency of the second pulse 2, and the wavelength of the second pulse 2 will correspondingly become half, one-third, or one-quarter of its original value. This application does not limit the specific multiplication value. Frequency multiplier 430 includes, but is not limited to, PPLN, MgO:PPLN, BBO, BIBO, KTP, LBO, PCF, or HNLF.

[0137] The second amplifier 440 amplifies the energy of the third pulse to obtain a fourth pulse. The second amplifier 440 includes a crystal. The center wavelength range of the fourth pulse can be 750 nm to 810 nm, and the energy range of the fourth pulse can be 10 μJ to 1000 μJ. The crystal includes emerald green, sapphire, or ruby. Using emerald green, sapphire, or ruby ​​as an amplifier can reduce the nonlinear effects of the pulsed laser in the gain medium, thereby obtaining a high-power, high-energy pulsed laser.

[0138] Figure 9 This is a schematic diagram of the specific structure of a laser 400 provided in an embodiment of this application.

[0139] The first pulse 1 provided by the laser seed source 410 is a femtosecond or picosecond pulse with a center wavelength around 1560nm. It can be a SESAM or NALM mode-locked pulse with all-fiber optics, and its spectral characteristics can be narrow or wide (≥5nm).

[0140] The pulse stretcher 415 includes a pulse stretching fiber, which may be a section of highly nonlinear fiber. The pulse stretching fiber receives a first pulse 1 and amplifies its width in the time domain to obtain a first pulse 2.

[0141] The first amplifier 420 includes a single-mode pump, a single-mode fiber, a multi-mode pump, and a double-clad fiber. The first pulse 2 is first amplified by the single-mode pump and the single-mode fiber, and then further amplified by the multi-mode pump and the double-clad fiber to obtain the second pulse 1. The energy range of the second pulse 1 can be 0.1 μJ to 10 μJ.

[0142] Compressor 450 includes a pair of diffraction gratings for reducing the width of the second pulse 1 in the time domain to obtain the second pulse 2. Pulse stretcher 415 amplifies the width of the pulse in the time domain, and compressor 450 can recompress the pulse to help restore the short-time domain characteristics of the pulse.

[0143] The frequency multiplier 430 can select frequency doubling crystals including, but not limited to, PPLN, MgO:PPLN, BBO, BIBO, KTP, LBO, PCF, or HNLF. For example, the frequency multiplier 430 doubles the frequency of the second pulse 2, thereby halving the wavelength, resulting in a third pulse with a wavelength around 780 nm.

[0144] The second amplifier 440 may include sapphire. The third pulse, after being pumped by visible light and passed through the sapphire, is absorbed, excited, and amplified in the sapphire, generating a fourth pulse with an average power greater than 10W, a pulse energy greater than 100uJ, and a center wavelength around 780nm. The visible light pump can be a high-brightness light source in the 600nm band, such as a laser diode.

[0145] The laser 400 provided in this application embodiment introduces a frequency multiplier 430 before the second amplifier 440, which can shorten the wavelength of the pulse, thereby using sapphire to further amplify the energy of the pulse. The way sapphire amplifies the pulse energy can reduce the nonlinear effect of the pulsed laser in the gain medium, thereby obtaining a high-power, high-energy pulsed laser.

[0146] Meanwhile, the pulse stretcher 415 of the laser 400 employs a section of highly nonlinear fiber. By adjusting the length of the highly nonlinear single-mode fiber, the pulse stretching width can be controlled. Since highly nonlinear single-mode fibers generally have large dispersion, the laser 400 can achieve large-range active tuning of the pulse width, which simplifies the complexity of the laser and reduces cost and power consumption.

[0147] In the laser 400 provided in this application embodiment, a diffraction grating pair is used as a large negative dispersion element, which can generate high-power pulses of picosecond and below. Combined with the second-order and third-order precise matching or control of the pulse stretcher 415, high-quality pulse output can be achieved.

[0148] Figure 10 This is a schematic diagram of another laser structure provided in an embodiment of this application.

[0149] The laser 500 includes a laser seed source 510, a first amplifier 520, a frequency multiplier 530, a second amplifier 540, and a compressor 550.

[0150] The laser seed source 510 is used to provide the first pulse. The center wavelength range of the first pulse can be 1500nm to 1620nm. The laser seed source 510 can adopt an all-fiber SESAM or NALM mode-locking method.

[0151] The laser seed source 510 includes either a femtosecond mode-locked laser seed source or a picosecond mode-locked laser seed source. When the laser seed source 510 is a femtosecond mode-locked laser seed source, it can provide femtosecond-level pulses; when the laser seed source 510 is a picosecond mode-locked laser seed source, it can provide picosecond-level pulses.

[0152] The first amplifier 520 is used to amplify the energy of the first pulse to obtain the second pulse. The energy range of the second pulse can be 0.1 μJ to 10 μJ.

[0153] For example, the first amplifier 520 may include any one or more of the following: single-mode fiber and double-clad fiber. In some possible application scenarios, the first amplifier 520 includes both single-mode fiber and double-clad fiber. The first pulse can be amplified by passing through the single-mode fiber first, and then further amplified by passing through the double-clad fiber to obtain the second pulse. In other possible application scenarios, the first amplifier 520 includes multiple single-mode fibers. The first pulse can be amplified by passing through some single-mode fibers first, and then further amplified by passing through another portion of single-mode fibers to obtain the second pulse. In still other possible application scenarios, the first amplifier 520 includes multiple double-clad fibers. The first pulse can be amplified by passing through some double-clad fibers first, and then further amplified by passing through another portion of double-clad fibers to obtain the second pulse.

[0154] Frequency multiplier 530 is used to amplify the frequency of the second pulse to obtain the third pulse. Frequency multiplier 530 is a device used to double the frequency of an optical signal (i.e., perform frequency multiplication). Since the speed of light = wavelength × frequency, when the frequency is doubled, the wavelength is halved. For example, frequency multiplier 530 can double, triple, or quadruple the frequency of the second pulse, and the wavelength of the second pulse will correspondingly become half, one-third, or one-quarter of its original value. This application does not limit the specific multiplication value. Frequency multiplier 530 includes, but is not limited to, PPLN, MgO:PPLN, BBO, BIBO, KTP, LBO, PCF, or HNLF.

[0155] The second amplifier 540 amplifies the energy of the third pulse to obtain a fourth pulse. The second amplifier 540 includes a crystal. The center wavelength range of the fourth pulse can be 750 nm to 810 nm, and the energy range of the fourth pulse can be 10 μJ to 1000 μJ. The crystal includes emerald green, sapphire, or ruby. Using emerald green, sapphire, or ruby ​​as an amplifier can reduce the nonlinear effects of the pulsed laser in the gain medium, thereby obtaining a high-power, high-energy pulsed laser.

[0156] Compressor 550 is used to reduce the width of the fourth pulse in the time domain. This compressor 550 includes, but is not limited to, diffraction grating pairs, fiber delayers, grating-prism compressors, or fiber dispersion compensators. In other possible applications, it is necessary to transmit short pulses with high peak power to improve transmission efficiency. In this case, compressor 550 can help maintain the short time-domain characteristics of the pulse to ensure efficient data transmission.

[0157] Figure 11 This is a schematic diagram of the specific structure of a laser 500 provided in an embodiment of this application.

[0158] The first pulse provided by the laser seed source 510 is a femtosecond or picosecond pulse with a center wavelength around 1560nm. It can use an all-fiber SESAM or NALM mode-locking method, and its spectral characteristics can be narrow or wide (≥5nm).

[0159] The first amplifier 520 includes a single-mode pump, a single-mode fiber, a multi-mode pump, and a double-clad fiber. The first pulse is first amplified by the single-mode pump and the single-mode fiber, and then further amplified by the multi-mode pump and the double-clad fiber to obtain the second pulse. The energy range of the second pulse can be 0.1 μJ to 10 μJ.

[0160] The frequency multiplier 530 can select frequency doubling crystals including, but not limited to, PPLN, MgO:PPLN, BBO, BIBO, KTP, LBO, PCF, or HNLF. For example, the frequency multiplier 530 doubles the frequency of the second pulse, thereby halving the wavelength, resulting in a third pulse with a wavelength around 780 nm.

[0161] The second amplifier 540 may include emerald green. The third pulse, after being pumped by visible light and passed through the emerald green, is absorbed, excited, and amplified in the emerald green, generating a fourth pulse with an average power greater than 10W, a pulse energy greater than 100uJ, and a center wavelength around 780nm. The visible light pump can be a high-brightness light source in the 600nm band, such as a laser diode.

[0162] Compressor 550 includes a pair of diffraction gratings for reducing the width of the fourth pulse in the time domain. When it is necessary to transmit short pulses with high peak power to improve transmission efficiency, compressor 550 can help maintain the short time-domain characteristics of the pulse to ensure efficient data transmission.

[0163] The laser 500 provided in this application embodiment introduces a frequency multiplier 530 before the second amplifier 540, which can shorten the wavelength of the pulse, thereby using alexandrite to further amplify the energy of the pulse. The way alexandrite amplifies the pulse energy can reduce the nonlinear effect of the pulsed laser in the gain medium, thereby obtaining a high-power, high-energy pulsed laser.

[0164] In the laser 500 provided in this application embodiment, a diffraction grating pair is used as a large negative dispersion element, which can generate picosecond and lower high-power pulses and realize high-energy pulse output.

[0165] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the device described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0166] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A laser, characterized by, include: A laser seed source, used to provide the first pulse; The first amplifier is used to amplify the energy of the first pulse to obtain the second pulse; A frequency multiplier is used to amplify the frequency of the second pulse to obtain the third pulse; A second amplifier, comprising a crystal, is used to amplify the energy of the third pulse to obtain a fourth pulse.

2. The laser according to claim 1, characterized in that, The crystals include emerald, sapphire, or ruby.

3. The laser according to claim 1 or 2, characterized in that, It also includes a pulse stretcher for amplifying the width of the first pulse in the time domain.

4. The laser according to claim 3, characterized in that, The pulse stretcher includes any one or more of the following: single-mode fiber, chirped fiber Bragg grating (CFBG), and diffraction grating.

5. The laser according to any one of claims 1 to 4, characterized in that, It also includes a compressor for reducing the width of the second pulse in the time domain or reducing the width of the fourth pulse in the time domain.

6. The laser according to claim 5, characterized in that, The compressor includes a diffraction grating pair, an optical fiber delayer, a grating-prism compressor, or an optical fiber dispersion compensator.

7. The laser according to any one of claims 1 to 6, characterized in that, The frequency multiplier includes periodically polarized lithium niobate crystal PPLN, periodically polarized magnesium oxide-doped lithium niobate crystal MgO:PPLN, barium metaborate crystal BBO, bismuth borate BIBO, potassium titanyl phosphate KTP, lithium triborate LBO, photonic crystal fiber PCF, or highly nonlinear fiber HNLF.

8. The laser according to any one of claims 1 to 7, characterized in that, The laser seed source includes a femtosecond mode-locked laser seed source or a picosecond mode-locked laser seed source.

9. The laser according to any one of claims 1 to 8, characterized in that, The first amplifier includes any one or more of the following: single-mode fiber, double-clad fiber.

10. The laser according to any one of claims 1 to 9, characterized in that, The center wavelength range of the fourth pulse is 750nm to 810nm.

11. The laser according to any one of claims 1 to 10, characterized in that, The center wavelength range of the first pulse is 1500nm to 1620nm.

12. The laser according to any one of claims 1 to 11, characterized in that, The energy range of the second pulse is 0.1 μJ to 10 μJ.

13. The laser according to any one of claims 1 to 12, characterized in that, The energy range of the fourth pulse is 10μJ to 1000μJ.

14. A method for generating laser light, characterized in that, include: The laser seed source in the laser provides the first pulse; The first amplifier in the laser amplifies the energy of the first pulse to obtain the second pulse; The frequency multiplier in the laser amplifies the frequency of the second pulse to obtain the third pulse; The second amplifier in the laser amplifies the energy of the third pulse to obtain a fourth pulse, and the second amplifier includes a crystal.

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