Frequency doubling laser equipment

Abstract

The utility model discloses frequency doubling laser equipment, which comprises a seed light source, a pre-amplifier, a main amplifier, a first-stage frequency doubling module, a second-stage frequency doubling module and a third-stage frequency doubling module, the seed light source outputs initial laser, and the wavelength range of the initial laser is 1546.944 + / -8nm; the seed light source is sequentially connected with the pre-amplifier and the main amplifier, and each of the pre-amplifier and the main amplifier comprises a gain fiber and a pumping diode; the main amplifier is connected with the first-stage frequency doubling module, the first-stage frequency doubling module, the second-stage frequency doubling module and the third-stage frequency doubling module are sequentially connected, the third-stage frequency doubling module outputs laser, and the wavelength range of the laser is 193.368 + / -1nm. The frequency doubling laser device can improve the stability and the output power of generated laser, and reduce the overall structure complexity.

Description

Technical Field

[0001] The utility model belongs to the technical field of lasers, and in particular relates to a frequency doubling laser device. Background Art

[0002] 193nm lasers play a key role in semiconductor lithography, especially in the process of manufacturing microprocessors and other high-precision electronic components. In addition, the laser is also widely used in ophthalmic surgery, such as LASIK surgery, as well as spectral analysis and material processing in scientific research. However, existing 193nm lasers still have problems with low laser stability and output power, high system complexity and high operating costs. For example, invention patent CN105191026A discloses a laser for generating an output wavelength of about 193.4nm, including a fundamental laser, an optical parameter generator, a fourth harmonic generator and a mixing module. The optical parameter generator coupled to the fundamental laser can generate a down-converted signal. The fifth harmonic generator that can be coupled to the optical parameter generator or the fundamental laser can generate a fifth harmonic. The mixing module coupled to the optical parameter generator and the fifth harmonic generator can generate a laser output at a frequency equal to the sum of the fifth harmonic and the frequency of the down-converted signal. The solution it adopts requires four nonlinear frequency conversions before the laser wavelength can be converted from infrared to around 193nm. The structure is relatively complex. In addition, nonlinear frequency conversion processes such as optical parameter generation, frequency doubling and sum frequency are required, which increases the cost and difficulty of implementing the solution.

[0003] Therefore, how to provide a device with a simple structure and stable laser output is an urgent problem to be solved by those skilled in the art. Utility Model Content

[0004] In view of the defects existing in the prior art, the utility model provides a frequency doubling laser device, which can improve the stability and output power of generating 193nm laser and reduce the overall structural complexity.

[0005] The utility model provides a frequency doubling laser device, comprising a seed light source, a pre-amplifier, a main amplifier, a primary frequency doubling module, a secondary frequency doubling module and a tertiary frequency doubling module;

[0006] The seed light source outputs an initial laser, and the wavelength range of the initial laser is 1546.944±8nm;

[0007] The seed light source is connected to the pre-amplifier and the main amplifier in sequence, and both the pre-amplifier and the main amplifier include a gain optical fiber and a pump diode;

[0008] The main amplifier is connected to the first-stage frequency doubling module, the first-stage frequency doubling module, the second-stage frequency doubling module and the third-stage frequency doubling module are connected in sequence, and the third-stage frequency doubling module outputs laser light, and the wavelength range of the laser light is 193.368±1nm.

[0009] Furthermore, the seed light source is a single-frequency continuous light laser, a single-frequency pulse laser based on gain modulation or intensity modulation, a mode-locked laser or a Q-switched laser.

[0010] Furthermore, the single-frequency continuous light laser is a single-frequency distributed feedback fiber laser, a single-frequency fixed external cavity semiconductor laser, a single-frequency tunable external cavity semiconductor laser or a single-frequency distributed feedback semiconductor laser.

[0011] Furthermore, the laser device includes a frequency stabilizer connected to the seed light source.

[0012] Furthermore, the frequency stabilizer includes a seed laser optical path and a reference laser optical path, and the initial laser wavelength range of the seed laser optical path output is 1546.944±8nm.

[0013] Furthermore, the reference laser optical path is connected to the seed laser optical path, and the output reference laser wavelength range is 1546.944±8nm.

[0014] Furthermore, the seed laser optical path includes: a first beam combiner, a first photodetector, a frequency divider, a frequency and phase detector, and a first servo element connected in sequence, and the input of the first beam combiner and the output of the first servo element are both connected to the seed light source.

[0015] Furthermore, the reference laser optical path includes a reference light source, a beam splitter, an optoelectronic modulator, an absorption cell, a second photodetector, a mixer, a low-pass filter and a second servo element connected in a ring shape in sequence, the output of the beam splitter is connected to the input of the first beam combiner, and the output of the optoelectronic modulator is connected to the input of the mixer; the absorption spectrum of the absorption cell corresponds to a wavelength of 1546.690nm.

[0016] Furthermore, the pre-amplifier and the main amplifier both include a gain fiber, a pump filter, an isolator and a pump unit. The gain fiber, the pump filter and the isolator are connected in sequence. The gain fiber is connected to the seed light source, the isolator is connected to the main amplifier, the pump unit is arranged between the seed light source and the gain fiber, and / or between the gain fiber and the pump filter, and the pump unit includes a connected pump diode and a second combiner.

[0017] Furthermore, in the pre-amplifier, the length of the gain fiber is not greater than 30m, the output power of the pump diode is greater than 200mW, the wavelength is 900-1030nm or 1450-1540nm, the gain fiber has a core and / or cladding absorption greater than 0.5dB / m at 1530nm, the pump light transmittance of the second combiner is greater than 80%, and the signal light transmittance is greater than 80%.

[0018] Furthermore, in the main amplifier, the length of the gain fiber is not greater than 30m, the output power of the pump diode is greater than 2W, the wavelength is 900-1030nm or 1450-1540nm, the cladding absorption of the gain fiber at 1530nm is greater than 0.16dB / m, the pump light transmittance of the second combiner is greater than 80%, and the signal light transmittance is greater than 80%.

[0019] Furthermore, the first-level frequency doubling module outputs a first-level frequency doubling laser, the wavelength range of the first-level frequency doubling laser is 773.472±4nm, and the power is not more than 60W; the first-level frequency doubling module is single-pass or multi-pass frequency doubling, and the first-level frequency doubling module includes at least one frequency doubling crystal and / or waveguide with a length of 1-70mm, and the incident and exit surfaces are coated with high-transmittance films, and the transmittance is greater than 95%.

[0020] Furthermore, the secondary frequency doubling module outputs a secondary frequency doubling laser, the wavelength range of the secondary frequency doubling laser is 386.736±2nm, and the power is not more than 45W; the secondary frequency doubling module is resonant frequency doubling, and the secondary frequency doubling module includes at least one frequency doubling crystal with a length of 1-70mm, and the incident and exit surfaces are coated with a high-transmittance film or have a Brewster angle, and the transmittance is greater than 95%.

[0021] Furthermore, the three-stage frequency doubling module outputs laser light with a wavelength range of 193.368±1nm and a power of not less than 1μW; the three-stage frequency doubling module is resonant frequency doubling, and the three-stage frequency doubling module includes at least one frequency doubling crystal with a length of 0.1-70mm, and the incident and exit surfaces are coated with a high-transmittance film or have a Brewster angle, and the transmittance is greater than 95%.

[0022] Furthermore, the laser device includes a plurality of cavity locking modules, the secondary frequency doubling module and the tertiary frequency doubling module are both connected to cavity locking modules, and the cavity locking modules are PDH, HC frequency locking, Lock in or dither locking.

[0023] The utility model provides a frequency doubling laser device, which has at least the following beneficial effects:

[0024] (1) By performing secondary amplification and tertiary frequency doubling on the seed light source, the laser in the range of 1546.944±8nm can be converted into a laser in the range of 193.368±1nm for output, which has the effect of improving the stability and power of the output laser. In addition, the overall structure is simpler than the existing fourth-order nonlinear frequency conversion scheme, thereby reducing the cost.

[0025] (2) The power of the laser is appropriately amplified by the pre-amplifier, and then amplified to the predetermined power by the main amplifier. The power can be gradually increased without exceeding the thermal damage threshold of the medium, thus avoiding thermal management problems and improving equipment stability and amplification efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic diagram of a frequency doubling laser device provided by the utility model;

[0027] Figure 2 This is a schematic diagram of a frequency stabilizer provided by the utility model. DETAILED DESCRIPTION

[0028] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the drawings and specific implementation methods of the specification. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0029] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "said" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings, and "multiple" generally includes at least two.

[0030] It should also be noted that the term "includes", "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, so that a commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprising a ..." do not exclude the existence of other identical elements in the commodity or device including the elements.

[0031] See also Figure 1As shown, the utility model provides a frequency doubling laser device, comprising a seed light source, a preamplifier, a main amplifier, a primary frequency doubling module, a secondary frequency doubling module and a tertiary frequency doubling module connected in sequence; the seed light source outputs an initial laser within the range of 1546.944±8nm; the initial laser within the range of 1546.944±8nm is amplified by the preamplifier and the main amplifier for secondary power amplification, and then undergoes tertiary frequency doubling by the primary frequency doubling module, the secondary frequency doubling module and the tertiary frequency doubling module to output a laser within the range of 193.368±1nm.

[0032] Among them, the seed light source is a single-frequency continuous light laser, a single-frequency pulse laser based on gain modulation or intensity modulation, a mode-locked laser or a Q-switched laser. The single-frequency continuous light laser is a single-frequency distributed feedback fiber laser, a single-frequency fixed external cavity semiconductor laser, a single-frequency tunable external cavity semiconductor laser or a single-frequency distributed feedback semiconductor laser. The single-frequency distributed feedback fiber laser is an all-fiber structure, and the initial laser is generated by directly writing a phase-shifted fiber Bragg grating on an erbium-doped fiber. The single-frequency fixed external cavity semiconductor laser is based on a semiconductor gain chip, and the initial laser output is achieved through external feedback and filtering. The single-frequency tunable external cavity semiconductor laser is based on a laser diode with a built-in semiconductor gain chip, and the initial laser output is achieved through external feedback and filtering. The single-frequency distributed feedback semiconductor laser uses the characteristics of the short length of the semiconductor laser cavity to make the frequency interval between adjacent longitudinal modes larger, introduces refractive index modulation in the gain chip, forms a grating, realizes the integration of gain and feedback, and finally achieves initial laser output.

[0033] The laser device includes a frequency stabilizer connected to the seed light source, the frequency stabilizer includes a seed laser optical path and a reference laser optical path, the seed laser optical path is connected to the seed light source, the reference laser optical path is connected to the seed laser optical path, and is used to generate a reference frequency laser of a preset wavelength and input it into the seed laser optical path, and the seed laser optical path outputs an initial laser of a stable wavelength based on the reference frequency laser. Figure 2 As shown, the seed laser optical path includes: a first beam combiner, a first photodetector, a frequency divider, a frequency and phase detector, and a first servo element connected in sequence, and the input of the first beam combiner and the output of the first servo element are both connected to the seed light source; the reference laser optical path includes a reference light source, a beam splitter, a photoelectric modulator, an absorption cell, a second photodetector, a mixer, a low-pass filter and a second servo element connected in a ring shape in sequence, the output of the beam splitter is connected to the input of the first beam combiner, and the output of the photoelectric modulator is connected to the input of the mixer; the absorption spectrum of the absorption cell corresponds to a wavelength of 1546.690nm.

[0034] Both the seed light source and the reference light source can achieve initial laser output near 1546.944nm. The reference laser output by the reference light source is first split into two paths by a beam splitter, the first path is combined with the seed light source output, and the second path passes through the EOM (electro-optic modulator). The EOM receives the modulation signal, so that the reference light source generates frequency sidebands after the beam splitting passes through. The laser after passing through the EOM enters the HCN absorption cell, H 13 C 14 The corresponding wavelength of the 2μ3P6 line in the N molecule absorption spectrum is 1546.690nm. The laser signal output by the HCN absorption cell is input into PD2 (the second photodetector), and then mixed with the modulation signal to obtain the sum frequency signal and the difference frequency signal. After low-pass filtering, the difference frequency signal is fed back to the second servo element, and then the second servo element outputs a frequency locking signal to the reference light source, so that the laser wavelength of the reference light source can be locked at 1546.690nm.

[0035] The wavelength-locked reference light source and seed light source are combined into the same optical fiber through a beam combiner and input into PD1 (first photodetector) to obtain a beat signal of the difference in two laser frequencies, which is then divided into eight by a frequency divider to reduce the frequency of the beat signal. The reference signal outputs a stable signal with a frequency of 4GHz, which is input into the frequency detector and phase detector together with the reduced-frequency beat signal to generate an error signal that is input into the first servo element. The first servo element then outputs a frequency locking signal to the seed light source to lock the laser frequency of the seed light source. At this time, the output laser frequency difference between the seed light source and the reference light source is locked at 32GHz. Since the wavelength of the reference light source is locked at 1546.690nm, when the laser frequency of the seed light source is less than that of the reference light source, the initial laser wavelength output by the seed light source can be locked at 1546.944nm.

[0036] The frequency stabilizer of the utility model is used to lock the output wavelength of the seed light source, and realize the locking of the final 193nm laser output wavelength. After locking, the wavelength is within the range of 193.368±1nm. The reference source can be found in the range of the fundamental frequency light, the first-order frequency-doubled light, the second-order frequency-doubled light, and the third-order frequency-doubled light, and the fundamental frequency light wavelength can be feedback-locked, and finally the wavelength locking of any level of initial laser can be realized.

[0037] The pre-amplifier and the main amplifier both include a gain fiber, a pump filter, an isolator and a pump unit. The gain fiber, the pump filter and the isolator are connected in sequence. The gain fiber is connected to the seed light source, and the isolator is connected to the main amplifier. The pump unit is arranged between the seed light source and the gain fiber, and / or between the gain fiber and the pump filter. The pump unit includes a connected pump diode and a second combiner.

[0038] Among them, the pump diode emits near-infrared light to achieve a population inversion distribution in the gain fiber, providing the necessary energy for the generation of the laser. The beam combiner effectively combines the pump light with the initial laser so that the pump light can enter the gain fiber. The beam combiner is usually able to withstand high-power pump light while maintaining the transmission efficiency of the initial laser. The gain fiber can achieve power amplification and is doped with rare earth elements that can amplify the optical signal. When the pump light is absorbed, the rare earth ions in the gain fiber will transition from the excited state to the ground state, releasing photons of the same frequency as the initial laser, thereby amplifying the initial laser passing through. The role of the pump filter is to filter out the unwanted pump light in the laser output. Since the wavelength of the pump light is different from the wavelength of the laser output, the filter can ensure that only the laser output is transmitted, and the pump light is effectively blocked to prevent it from interfering with the system or application. The isolator is used to ensure that the light propagates in only one direction to prevent the reflection of the light back to the gain fiber or pump diode, which may cause instability or damage the efficiency of the laser.

[0039] The preamplifier is an all-fiber structure, which can include one or more stages of amplification according to power requirements. The basic structure of each stage is the same, and the final output power is greater than 1W. In the preamplifier, the gain fiber length is no more than 30m, the output power of the pump diode is greater than 200mW, the wavelength is 900-1030nm or 1450-1540nm, the gain fiber core and / or cladding absorption at 1530nm is greater than 0.5dB / m, the pump light transmittance of the second combiner is greater than 80%, and the signal light transmittance is greater than 80%;

[0040] The main amplifier is an all-fiber structure, which can include one or more stages of amplification according to power requirements. The basic structure of each stage is the same, and the final output power is 1-90W. In the main amplifier, the gain fiber length is no more than 30m, the output power of the pump diode is greater than 2W, the wavelength is 900-1030nm or 1450-1540nm, the gain fiber cladding absorption at 1530nm is greater than 0.16dB / m, the pump light transmittance of the second combiner is greater than 80%, and the signal light transmittance is greater than 80%.

[0041] The first-level frequency doubling module converts the wavelength of the initial laser from 1546.944±8nm to a first-level frequency doubling laser of 773.472±4nm; the first-level frequency doubling module is single-pass or multi-pass frequency doubling, and the first-level frequency doubling module includes at least one frequency doubling crystal and / or waveguide, and each frequency doubling crystal or waveguide is temperature-controlled to improve the frequency conversion efficiency and output power stability. The specific structure can be cascade, folding, cascade plus folding, etc. The length of the frequency doubling crystal or waveguide is 1-70mm, and the incident and exit surfaces are coated with high-transmittance films, and the transmittance is greater than 95%; the power of the first-level frequency doubling module outputting a wavelength of 773.472±4nm of the first-level frequency doubling laser is not more than 60W.

[0042] The secondary frequency doubling module converts the wavelength of the primary frequency doubling laser from the range of 773.472±4nm to the secondary frequency doubling laser of 386.736±2nm; the secondary frequency doubling module is a resonant frequency doubling module, and the secondary frequency doubling module includes at least one frequency doubling crystal, the length of the frequency doubling crystal is 1-70mm, the incident and exit surfaces are coated with high-transmittance films or have Brewster angles, and the transmittance is greater than 95%; each frequency doubling crystal or waveguide is temperature-controlled to improve the frequency conversion efficiency and output power stability. The resonant cavity contains PZT (piezoelectric ceramics), and the PDH technology is used to lock the resonant cavity mode and laser frequency. The power of the secondary frequency doubling module outputting the secondary frequency doubling laser with a wavelength of 386.736±2nm is not more than 45W.

[0043] The three-stage frequency doubling module converts the wavelength of the second-stage frequency doubling laser from the range of 386.736±2nm to 193.368±1nm; the three-stage frequency doubling module is resonant frequency doubling, and the three-stage frequency doubling module includes at least one frequency doubling crystal, the length of the frequency doubling crystal is 0.1-70mm, the incident and exit surfaces are coated with high-transmittance films or have Brewster angles, and the transmittance is greater than 95%; each frequency doubling crystal or waveguide is temperature-controlled to improve the frequency conversion efficiency and output power stability. The resonant cavity contains PZT (piezoelectric ceramics), and the PDH technology is used to lock the resonant cavity mode and laser frequency. The power of the laser with a wavelength of 193.368±1nm output by the three-stage frequency doubling module is not less than 1μW.

[0044] When the seed light source is a single-frequency distributed feedback fiber laser, the frequency sideband is generated by modulating the EOM in the frequency stabilizer, and the resonant cavity mode and laser frequency are locked through the PDH technology to achieve stable and efficient frequency doubled laser output. When the seed light source is a single-frequency fixed external cavity semiconductor laser, a single-frequency adjustable external cavity semiconductor laser or a single-frequency distributed feedback semiconductor laser, the frequency sideband is generated by modulating the gain chip current or the EOM in the frequency stabilizer to form an error signal. Through the PDH technology, the resonant cavity length is changed by real-time tuning of the PZT to achieve the resonant cavity mode and laser frequency locking, and stable and efficient frequency doubled laser output.

[0045] The laser device includes multiple cavity locking modules. The secondary frequency doubling module and the tertiary frequency doubling module are both connected to cavity locking modules. The cavity locking modules are PDH, HC frequency locking, Lock in or jitter locking.

[0046] The process of the laser device of the utility model generating 193nm laser is as follows:

[0047] The seed light source outputs the initial laser of any wavelength within the range of 1546.944±8nm, and first passes through the pre-amplifier for power pre-amplification, the output power can be greater than 1W, and then enters the main amplifier for further power amplification, the output power can reach 80W. Then the initial laser passes through the first-level frequency doubling module, the second-level frequency doubling module and the third-level frequency doubling module in turn for three-level frequency doubling, first entering the first-level frequency doubling module, the first-level frequency doubling is single-pass or multi-pass frequency doubling, the fundamental frequency light and the frequency doubling light pass through the frequency doubling crystal a limited number of times, the output power can reach 60W, the wavelength is within the range of 773.472±4nm, the second-level frequency doubling is resonant frequency doubling, the output power can reach 45W, the wavelength is within the range of 386.736±2nm, the third-level frequency doubling is also resonant frequency doubling, the output power can be greater than 50mW, the wavelength is within the range of 193.368±1nm. The second-stage resonant frequency doubling and the third-stage resonant frequency doubling are equipped with a cavity locking module to achieve the matching of the resonant frequency doubling cavity mode and the laser frequency. In addition, the laser frequency of the seed light source is locked by a frequency stabilizer, and the final output 193nm laser frequency is also locked.

[0048] Although preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they are aware of the basic creative concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention. Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A frequency doubling laser device, characterized in that: It includes a seed light source, a pre-amplifier, a main amplifier, a first-stage frequency multiplication module, a second-stage frequency multiplication module and a third-stage frequency multiplication module; The seed light source outputs an initial laser, and the wavelength range of the initial laser is 1546.944±8nm; The seed light source is connected to the pre-amplifier and the main amplifier in sequence, and both the pre-amplifier and the main amplifier include a gain optical fiber and a pump diode; The main amplifier is connected to the first-stage frequency doubling module, the first-stage frequency doubling module, the second-stage frequency doubling module and the third-stage frequency doubling module are connected in sequence, and the third-stage frequency doubling module outputs laser light, and the wavelength range of the laser light is 193.368±1nm.

2. The frequency-doubling laser device according to claim 1, characterized in that: The seed light source is a single-frequency continuous light laser, a single-frequency pulse laser based on gain modulation or intensity modulation, a mode-locked laser or a Q-switched laser.

3. The frequency-doubling laser device according to claim 1, characterized in that: The laser device also includes a frequency stabilizer connected to the seed light source.

4. The frequency-doubling laser device according to claim 3, characterized in that: The frequency stabilizer includes a seed laser optical path and a reference laser optical path, and the initial laser wavelength range output by the seed laser optical path is 1546.944±8nm; The reference laser optical path is connected to the seed laser optical path, and the output reference laser wavelength range is 1546.944±8nm; The seed laser optical path includes: a first beam combiner, a first photodetector, a frequency divider, a frequency and phase detector, and a first servo element connected in sequence, and the input of the first beam combiner and the output of the first servo element are both connected to the seed light source; The reference laser optical path includes a reference light source, a beam splitter, an optoelectronic modulator, an absorption cell, a second photodetector, a mixer, a low-pass filter and a second servo element which are connected in a ring shape in sequence. The output of the beam splitter is connected to the input of the first beam combiner, and the output of the optoelectronic modulator is connected to the input of the mixer.

5. The frequency-doubling laser device according to claim 1, characterized in that: In the pre-amplifier, the length of the gain fiber is not more than 30m, the output power of the pump diode is greater than 200mW, the wavelength is 900-1030nm or 1450-1540nm, the gain fiber core and / or cladding absorption at 1530nm is greater than 0.5dB / m, the pump light transmittance of the second combiner is greater than 80%, and the signal light transmittance is greater than 80%.

6. The frequency-doubling laser device according to claim 1, characterized in that: In the main amplifier, the gain fiber length is no more than 30m, the output power of the pump diode is greater than 2W, the wavelength is 900-1030nm or 1450-1540nm, the gain fiber cladding absorption at 1530nm is greater than 0.16dB / m, the pump light transmittance of the second combiner is greater than 80%, and the signal light transmittance is greater than 80%.

7. The frequency-doubling laser device according to claim 1, characterized in that: The first-level frequency doubling module outputs first-level frequency doubling laser, the wavelength range of the first-level frequency doubling laser is 773.472±4nm, and the power is not more than 60W; the first-level frequency doubling module is single-pass or multi-pass frequency doubling.

8. The frequency-doubling laser device according to claim 7, characterized in that: The secondary frequency doubling module outputs secondary frequency doubling laser, the wavelength range of the secondary frequency doubling laser is 386.736±2nm, and the power is not more than 45W.

9. The frequency-doubling laser device according to claim 8, characterized in that: The output laser power of the three-stage frequency doubling module is not less than 1μW.

10. The frequency-doubling laser device according to any one of claims 1 to 9, characterized in that: The laser device also includes a plurality of cavity locking modules. The secondary frequency doubling module and the tertiary frequency doubling module are both connected to cavity locking modules. The cavity locking modules are PDH, HC frequency locking, Lockin or dither locking.

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