Short-wavelength pulse laser

Abstract

The invention relates to the technical field of short-wavelength lasers, and discloses a short-wavelength pulse laser, which comprises a superfluorescence semiconductor laser used for modulating and outputting first pulse laser with a spectral width range as a first width range; the narrow-band filter is used for performing narrow-band filtering on the first pulse laser to obtain second pulse laser of which the spectral width range is a second width range, and the second width range is smaller than the first width range; the filtering and amplifying unit is used for carrying out narrow-band filtering and power amplification on the second pulse laser to obtain third pulse laser of which the spectral width range is a third width range, and the third width range is smaller than the second width range; and the frequency multiplication device is used for carrying out frequency multiplication on the third pulse laser to obtain short-wavelength pulse laser. According to the invention, an additional light modulator is not needed, and the complexity and the manufacturing cost of the short-wavelength pulse laser are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of short-wavelength lasers, and in particular to a short-wavelength pulse laser. Background Art

[0002] Currently, there are two ways to implement nanosecond pulse short-wavelength lasers, mainly divided into solid-state solutions and optical fiber solutions. Among them, the solid-state solution has more and more complex spatial devices due to its structural characteristics, and its stability is relatively poor. In general, solutions above 100W are difficult to implement.

[0003] In the related art, a technical solution is proposed to use an amplified spontaneous emission (ASE) light source based on narrowband filtering combined with an optical modulator to output a narrowband pulse seed light. The ASE light source generated by a fiber laser is also called a super-fluorescent fiber source (SFS). This solution cleverly utilizes the weak coherence of the ASE light source, so that the obtained pulse can still maintain a narrow spectral width during the amplification process, making it an ideal fundamental frequency light source for realizing high-efficiency pulse short-wavelength pulse lasers. However, since the narrowband ASE light source itself is a continuous output, it must be modulated into pulse light by an external optical modulator, which to a certain extent affects the system complexity of the laser. At the same time, due to the small modulation bandwidth of the acousto-optic device, generally only a rising edge of more than 10ns can be achieved, which limits the adjustable width range of the optical pulse output in the end. Although the electro-optic modulator has a higher switching rising edge, its insertion loss is large and its price is generally relatively high.

[0004] In summary, there is an urgent need for a laser suitable for generating short-wavelength pulses to solve the technical problem that the output of short-wavelength pulse light requires an external optical modulator, which increases the complexity of the laser. Summary of the invention

[0005] In view of this, the present invention provides a short-wavelength pulse laser to solve or partially solve the technical problem in the related art that an external optical modulator is required to output short-wavelength pulse light, thereby increasing the complexity of the laser.

[0006] The technical solution proposed by the present invention is as follows:

[0007] The invention provides a short-wavelength pulse laser, comprising: a super-fluorescent laser diode (SLD) for modulating and outputting a first pulse laser with a spectrum width range of a first width range; a narrow-band filter for performing narrow-band filtering on the first pulse laser to obtain a second pulse laser with a spectrum width range of a second width range, wherein the second width range is smaller than the first width range; a filtering and amplifying unit for performing narrow-band filtering and power amplification on the second pulse laser to obtain a third pulse laser with a spectrum width range of a third width range, wherein the third width range is smaller than the second width range; and a frequency doubling device for performing frequency doubling on the third pulse laser to obtain a short-wavelength pulse laser.

[0008] The invention discloses a short-wavelength pulse laser, which uses a superfluorescent semiconductor laser as a pulse seed light source. The superfluorescent semiconductor laser has a relatively wide spectral bandwidth (10nm to 100nm) and low temporal coherence. The spectral components per unit width in the spectrum are more stable in the time domain than the laser output by the common laser resonant cavity, and no violent sub-pulse phenomenon due to mode interference occurs. Meanwhile, the superfluorescent semiconductor laser can be directly modulated and output a first pulse laser, and the first pulse laser is filtered in sequence by a narrowband filter and a filter amplifier unit to obtain a second pulse laser and a third pulse laser with successively reduced spectral width ranges. Finally, the third pulse laser is frequency-multiplied by a frequency-multiplying device to obtain a high-power short-wavelength pulse laser. The invention can achieve the narrow spectral width after amplification, and the output short-wavelength pulse laser is stable, and a frequency-multiplying efficiency of up to 50%-60% can be achieved, and no external optical modulator is required, thereby reducing the complexity and manufacturing cost of the short-wavelength pulse laser.

[0009] In some optional embodiments, the first width ranges from 10 nm to 20 nm, the second width ranges from 1 nm to 2 nm, and the third width ranges from 0.01 nm to 0.5 nm.

[0010] By specifically defining the decrement of the spectral width range, the spectral characteristics of the laser can be more precisely controlled, stray light and noise can be reduced, and the monochromaticity and coherence of the laser can be improved.

[0011] In some optional embodiments, the central wavelength of the first laser is 1030 nm or 1064 nm.

[0012] By setting the central wavelength of the first laser to 1030nm or 1064nm, green light pulses can be output after subsequent frequency doubling, which can be widely used in various industrial scenarios.

[0013] In some optional embodiments, the filtering and amplifying unit includes a fiber circulator, a first active optical fiber, a first wavelength division multiplexer, a first pump source and a narrowband high-reflection grating, the first end of the fiber circulator is connected to the narrowband filter, the second end of the fiber circulator is connected to one end of the first active optical fiber, the other end of the first active optical fiber is connected to the first wavelength division multiplexer, the first pump source is used to input the first pump light to the first active optical fiber through the first wavelength division multiplexer, and the narrowband high-reflection grating is used to narrow-band filter the laser output by the first wavelength division multiplexer and reflect it back to the first wavelength division multiplexer, and enter the second active optical fiber through the first wavelength division multiplexer.

[0014] Through the design of the optical fiber circulator, the first active optical fiber, the first wavelength division multiplexer, the first pump source and the narrowband high-reflection grating, a second-order narrowband filtering double-pass amplification structure can be constructed, which realizes the laser's secondary filtering and amplification, improves the laser's power and further reduces the spectral width range.

[0015] In some optional embodiments, the short-wavelength pulse laser further includes a first isolator, which is disposed between the superfluorescent semiconductor laser and the narrow-band filter.

[0016] Providing the first isolator can prevent the reversely propagating light from being fed back to the super fluorescent semiconductor laser, thereby protecting the super fluorescent semiconductor laser from being damaged.

[0017] In some optional implementations, the short-wavelength pulse laser further includes a step-by-step amplifier, the input end of the step-by-step amplifier is connected to the output end of the filter amplifier unit, and the output end of the step-by-step amplifier is connected to the frequency multiplication device.

[0018] The power of the laser can be further increased through a step-by-step amplifier, allowing the laser to output higher energy pulsed lasers, which is suitable for applications requiring high-power lasers.

[0019] In some optional embodiments, the step-by-step amplifier includes a plurality of power amplifiers connected in series, each power amplifier includes a second pump source, a combiner and a second active optical fiber, one input end of the combiner is connected to the output end of the filter amplifier unit, another input end of the combiner is connected to the second pump source, and the output end of the combiner is connected to one end of the second active optical fiber.

[0020] By connecting multiple power amplifiers in series, the power of the laser can be gradually increased while maintaining the spectral characteristics of the laser.

[0021] In some optional implementations, a second isolator is provided between the first series-connected power amplifier and the filter amplification unit, and a third isolator is provided between each power amplifier.

[0022] By providing a second isolator between the power amplifier and the filter amplifier unit and a third isolator between the power amplifiers, reverse propagation and mutual interference of light can be prevented, thereby improving the stability of the laser output by the short-wavelength pulse laser.

[0023] In some optional implementations, the superfluorescent semiconductor laser, the narrowband filter, the filter amplifier unit, and the frequency doubling device are all polarization-maintaining devices.

[0024] The components of short-wavelength pulse lasers are all polarization-maintaining devices, which can maintain a narrow spectral width after amplification, and the output short-wavelength pulse laser is stable.

[0025] In some optional embodiments, the super fluorescent semiconductor laser is a butterfly packaged super fluorescent semiconductor laser.

[0026] The butterfly-packaged superfluorescent semiconductor laser outputs pulse seed light through direct modulation, and no optical modulator is required for subsequent configuration. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly express the technical solutions of the embodiments of the present invention, the drawings required for describing the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0028] Figure 1 Schematic diagram of the structure of a short-wavelength pulse laser in an embodiment of the present invention;

[0029] Figure 2 is a schematic diagram of the spectrum of the first pulse laser in an embodiment of the present invention;

[0030] Figure 3 is a schematic diagram of the spectrum of the second pulse laser in an embodiment of the present invention;

[0031] Figure 4 is a schematic diagram of the spectrum of the third pulse laser in an embodiment of the present invention;

[0032] Figure numerals: 11, superfluorescent semiconductor laser; 12, first isolator; 13, narrowband filter; 14, fiber circulator; 15, second isolator; 16, step-by-step amplifier; 17, frequency doubling device; 18, spectroscope; 19, output mirror; 21, first active optical fiber; 22, first wavelength division multiplexer; 23, narrowband high-reflection grating; 24, first pump source. DETAILED DESCRIPTION

[0033] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "upper", "lower", "left", "right", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0035] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can also be the internal connection of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0037] Currently, there are two ways to implement nanosecond pulse short-wavelength lasers, mainly divided into solid-state solutions and fiber-optic solutions.

[0038] The optical fiber solution has the advantages of high stability and good heat dissipation. In order to achieve a higher frequency doubling efficiency, the spectral width of the signal light source is generally required to be narrower, which is related to the smaller allowable bandwidth of the nonlinear crystal. Generally, the wider the fundamental frequency spectrum, the greater the phase mismatch and the lower the frequency doubling efficiency.

[0039] Therefore, one of the current solutions for realizing nanosecond short-wavelength lasers based on fiber solutions is based on direct modulation of DFB semiconductor lasers for amplification. Due to the single longitudinal mode structural characteristics of DFB semiconductor lasers, the spectral width of its direct output is generally in the order of hundreds of KHZ to several GHZ, which is 0.01nm when converted to nm units, and its spectrum cannot be naturally widened. Even under short pulse width modulation, its spectral width remains at the order of 0.01nm, and its spectrum will not be significantly widened by amplification of about 3dB, and it has very strong longitudinal mode control capabilities. Therefore, a serious SBS effect will occur during the amplification process, and it can generally only be used for narrow pulse width (less than 5ns) amplification, which limits the final output pulse energy. The pulse energy is low.

[0040] There is another method of adding phase modulation to the DFB semiconductor laser. This solution is complex and expensive because it requires devices such as electro-optical phase modulators, so it cannot be used on a large scale.

[0041] Related technologies also propose a technical solution of using an amplified spontaneous emission (ASE) light source based on narrowband filtering combined with an optical modulator to output narrowband pulse seed light. The ASE light source generated by a fiber laser is also called a super-fluorescent fiber source (SFS). This solution cleverly utilizes the weak coherence of the ASE light source, so that the obtained pulse can still maintain a narrow spectral width during the amplification process, making it an ideal fundamental frequency light source for realizing high-efficiency pulse short-wavelength pulse lasers. However, since the narrowband ASE light source itself is a continuous output, it must be modulated into pulse light by an external optical modulator, which to a certain extent affects the system complexity of the laser. At the same time, due to the small modulation bandwidth of the acousto-optic device, generally only a rising edge of more than 10ns can be achieved, which limits the adjustable width range of the optical pulse output in the end. Although the electro-optic modulator has a higher switching rising edge, its insertion loss is large and its price is generally relatively high.

[0042] Butterfly-packaged super-fluorescent laser diodes (SLDs) and super-fluorescent fiber light sources have similar output laser characteristics. They also have a wide spectral bandwidth (10nm to 100nm) and low temporal coherence, which is the property of ASE.

[0043] The internal characteristics of the butterfly-packaged superfluorescent semiconductor laser are different from those of the conventional Fabry-Perot resonant cavity semiconductor laser. There are no two matching resonant cavity reflection surfaces inside to form a resonant cavity mode (longitudinal mode), because once the resonant cavity mode is formed, it will lead to obvious spectral structure and spectral narrowing; instead, the optical feedback of the output end face is minimized by anti-reflection coating on the output end face and tilting or bending the waveguide, which ensures that the superfluorescent semiconductor laser will not reach the laser threshold within a larger pump current range. In essence, the superfluorescent semiconductor laser is a semiconductor optical amplifier without input signal, in which weak spontaneous radiation enters the waveguide mode and is further amplified by internal light to obtain a smooth output spectrum, and there is no amplified spontaneous radiation light output in any resonant mode (i.e., no longitudinal mode mode). The butterfly-packaged superfluorescent semiconductor laser can be directly modulated and output pulse seed light without the need for an external optical modulator, which is also the biggest advantage of this solution compared to the superfluorescent fiber light source solution plus external modulation solution.

[0044] In view of this, an embodiment of the present invention provides a short-wavelength pulse laser.

[0045] like Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, an embodiment of the present invention provides a short-wavelength pulse laser, including:

[0046] A superfluorescent semiconductor laser 11, used for modulating and outputting a first pulse laser having a spectral width range of a first width range;

[0047] A narrowband filter 13 is used to perform narrowband filtering on the first pulse laser to obtain a second pulse laser with a spectral width range of a second width range, where the second width range is smaller than the first width range;

[0048] A filtering and amplifying unit, used for performing narrow-band filtering and power amplification on the second pulse laser to obtain a third pulse laser having a spectrum width range of a third width range, wherein the third width range is smaller than the second width range;

[0049] The frequency doubling device 17 is used to double the frequency of the third pulse laser to obtain a short-wavelength pulse laser.

[0050] Specifically, the superfluorescent semiconductor laser 11 is a superfluorescent semiconductor laser 11 using a butterfly package. The butterfly-packaged superfluorescent semiconductor laser 11 and the superfluorescent fiber light source have similar output laser characteristics. They also have a wide spectral bandwidth (10nm to 100nm). At the same time, the superfluorescent semiconductor laser 11 has a random, continuous, and low coherence phase. Therefore, even if a narrow spectrum is output after spectral filtering, its original spectral components can still meet the broadening of nonlinear spectral modulation after amplification. Therefore, its SBS threshold will gradually increase with the spectrum broadening, and will not become the minimum threshold nonlinear effect that hinders system amplification.

[0051] The superfluorescent semiconductor laser 11 is a semiconductor optical amplifier without an input signal, in which weak spontaneous radiation enters the waveguide mode and is further amplified by internal light to obtain a smooth output spectrum without any resonant mode (ie, no longitudinal mode) of the amplified spontaneous radiation light output.

[0052] Therefore, the embodiment of the present invention uses the superfluorescent semiconductor laser 11 as a pulse seed light source to achieve a narrow spectral width after amplification, and finally achieve a frequency doubling efficiency of up to 50%-60%. In addition, the superfluorescent semiconductor laser 11 using a butterfly package can be directly modulated using a pulse current of a specific waveform and output a pulse seed light, i.e., a first pulse laser, without the need for an external optical modulator.

[0053] In one example, the peak power output by the superfluorescent semiconductor laser 11 under pulse modulation is about 1000mW, and the output spectrum width is between 10nm and 20nm. The desired pulse width can be obtained by directly modulating the laser, and the laser can also be subjected to high-precision waveform shaping to obtain a first pulse laser.

[0054] After the first pulse laser is output, in order to further reduce the spectral width, the first laser is narrow-band filtered through the narrow-band filter 13 to obtain a second pulse laser with a spectral width range of the second width range. In one example, the passband width of the narrow-band filter 13 is 1nm to 2nm, that is, the spectral width range of the output second pulse laser is 1nm to 2nm.

[0055] The second pulse laser is narrow-band filtered and power amplified by the filtering and amplifying unit to obtain a third pulse laser with a spectral width range of a third width range, wherein the second width range is smaller than the first width range, and the third width range is smaller than the second width range.

[0056] In one example, the bandpass width of the filter amplifier unit is 0.01 nm to 0.5 nm, that is, the spectrum width of the output third pulse laser is in the range of 0.01 nm to 0.5 nm. The filter amplifier unit can filter the laser and amplify the power of the laser.

[0057] By adopting a step-by-step narrow-band filtering method, the output third pulse laser has the characteristics of narrow line width and high side mode suppression ratio.

[0058] The third pulse laser serves as a pulse seed light, which can suppress the nonlinear spectral broadening as much as possible during the amplification process, and ultimately maintain a narrow output spectrum while obtaining a large pulse energy. The obtained pulse laser is very suitable as a fundamental frequency light source for nonlinear frequency conversion (i.e., frequency doubling) and achieves a higher frequency doubling efficiency.

[0059] The frequency doubling device 17 can be a nonlinear crystal such as a frequency doubling crystal, and can specifically realize functions such as double frequency and quadruple frequency, and the number of frequency doubling can be determined according to the required laser frequency. For example, a pulsed laser with a wavelength of 1064nm red light can be frequency-doubled to obtain a pulsed laser with a wavelength of 532nm green light.

[0060] Furthermore, the superfluorescent semiconductor laser 11 , the narrowband filter 13 , the filter amplification unit, and the frequency doubling device 17 are all polarization-maintaining devices.

[0061] Since the components of the short-wavelength pulse laser are all polarization-maintaining devices, it is possible to maintain a relatively narrow spectral width after amplification, and the output short-wavelength pulse laser is stable.

[0062] A short-wavelength pulse laser according to an embodiment of the present invention uses a superfluorescent semiconductor laser 11 as a pulse seed light source. The superfluorescent semiconductor laser 11 has a relatively wide spectral bandwidth (10nm to 100nm) and low temporal coherence. The spectral components per unit width in its spectrum are correspondingly more stable in the time domain than the laser output by an ordinary laser resonant cavity, and no violent sub-pulse phenomenon due to mode interference occurs. At the same time, the superfluorescent semiconductor laser 11 can be directly modulated and output a first pulse laser. The first pulse laser is filtered in sequence by a narrowband filter 13 and a filter amplifier unit to obtain a second pulse laser and a third pulse laser with successively reduced spectral width ranges. Finally, the third pulse laser is frequency-doubled by a frequency doubling device 17 to obtain a high-power short-wavelength pulse laser. The present invention can achieve a relatively narrow spectral width after amplification, and the output short-wavelength pulse laser is stable, and a frequency doubling efficiency of up to 50%-60% can be achieved. No external optical modulator is required, thereby reducing the complexity and manufacturing cost of the short-wavelength pulse laser.

[0063] In some embodiments, the filtering and amplifying unit includes a fiber circulator 14, a first active fiber 21, a first wavelength division multiplexer 22, a first pump source 24 and a narrowband high-reflection grating 23. The first end of the fiber circulator 14 is connected to the narrowband filter 13, the second end of the fiber circulator 14 is connected to one end of the first active fiber 21, and the other end of the first active fiber 21 is connected to the first wavelength division multiplexer 22. The first pump source 24 is used to input the first pump light to the first active fiber 21 through the first wavelength division multiplexer 22. The narrowband high-reflection grating 23 is used to narrow-band filter the laser output by the first wavelength division multiplexer 22 and reflect it back to the first wavelength division multiplexer 22, and enter the second active fiber through the first wavelength division multiplexer 22.

[0064] Specifically, the width of the narrowband high-reflection grating 23 is generally in the range of 0.01nm-0.5nm, the central wavelength is 1030nm or 1064nm, the pump light output by the first pump source 24 is a laser with a central wavelength of 980nm, and the pumping direction can be backward, forward, and bidirectional.

[0065] The light beam enters the first active optical fiber 21 from the optical fiber circulator 14, is amplified by the pump energy provided by the first pump source 24, and is transmitted to the narrowband high-reflection grating 23 for filtering, and then reflected back to the first active optical fiber 21. After being amplified again in the first active optical fiber 21, it is output from the optical fiber circulator 14. At this time, the output laser is the third pulse laser. The output power of the third pulse laser is about 100mW-500mW.

[0066] Through the design of the optical fiber circulator 14, the first active optical fiber 21, the first wavelength division multiplexer 22, the first pump source 24 and the narrowband high-reflection grating 23, a second-order narrowband filtering double-pass amplification structure can be constructed, which realizes the laser's secondary filtering and amplification, improves the laser's power and further reduces the spectral width range.

[0067] In some embodiments, the short-wavelength pulse laser further includes a first isolator 12 , which is disposed between the superfluorescent semiconductor laser 11 and the narrowband filter 13 .

[0068] The first isolator 12 is an optical isolator (ISO), which is a passive optical device that only allows light to be transmitted in one direction and blocks the transmission of light in the opposite direction.

[0069] The first isolator 12 can prevent the reversely propagating light from being fed back to the super fluorescent semiconductor laser 11 , thereby protecting the super fluorescent semiconductor laser 11 from being damaged.

[0070] In some embodiments, the short-wavelength pulse laser further includes a step-by-step amplifier 16 , the input end of the step-by-step amplifier 16 is connected to the output end of the filter amplifier unit, and the output end of the step-by-step amplifier 16 is connected to the frequency multiplication device 17 .

[0071] Specifically, the step-by-step amplifier 16 includes a plurality of power amplifiers connected in series, each power amplifier including a second pump source, a beam combiner and a second active optical fiber, one input end of the beam combiner is connected to the output end of the filter amplifier unit, the other input end of the beam combiner is connected to the second pump source, and the output end of the beam combiner is connected to one end of the second active optical fiber.

[0072] The third pulse laser output by the filter amplifier unit enters the second active optical fiber through an input end of the beam combiner and is amplified under the excitation of the pump energy of the second pump source.

[0073] Exemplarily, the wavelength of the pump light output by the second pump source is 975 nm or 915 nm, and it can be forward pumping or reverse pumping. Preferably, reverse pumping can be used to further reduce the nonlinear broadening of the spectrum.

[0074] By connecting multiple power amplifiers in series, the power of the laser can be gradually increased, allowing the laser to output higher energy pulsed lasers, which is suitable for applications that require high-power lasers, such as industrial processing, medical surgery, etc., while maintaining the spectral characteristics of the laser.

[0075] In some embodiments, a second isolator 15 is provided between the first series-connected power amplifier and the filter amplification unit, and a third isolator is provided between each power amplifier.

[0076] The second isolator 15 and the third isolator are the same as the first isolator 12, all of which use optical isolators ISO. By providing the second isolator 15 between the power amplifier and the filter amplifier unit and the third isolator between the power amplifiers, reverse propagation and mutual interference of light can be prevented, thereby improving the stability of the laser output by the short-wavelength pulse laser.

[0077] Furthermore, the short-wavelength pulse laser also includes a beam splitter 18 and an output mirror 19. The beam splitter 18 is mainly used to separate the output mixed light beam. The component is generally coated with a dielectric beam splitter film to reflect the short-wavelength light beam and transmit the infrared light beam. Generally, in order to reduce loss, the component is coated with a short-wavelength high-reflection film and an infrared light beam high-transmittance film.

[0078] The output mirror 19 is mainly used to output short-wavelength lasers. This component is generally coated with a dielectric spectroscopic film to further filter out infrared beams.

[0079] In some embodiments, the first width ranges from 10 nm to 20 nm, the second width ranges from 1 nm to 2 nm, and the third width ranges from 0.01 nm to 0.5 nm.

[0080] Furthermore, the central wavelength of the first pulsed laser is 1030nm or 1064nm. By setting the central wavelength of the first pulsed laser to 1030nm or 1064nm, green light pulses can be output after subsequent frequency doubling, which can be widely used in various industrial scenarios.

[0081] In one example, the central wavelength of the first pulse laser output by the superfluorescent semiconductor laser 11 is 1064nm, and the bandwidth range is about 10nm-20nm. The peak power output under pulse modulation is about 1000mW, and the second pulse laser with a bandwidth range of 1nm-2nm is filtered by the narrowband filter 13. Then, the third pulse laser with a bandwidth range of 0.01nm-0.05nm is filtered and amplified by the filter amplifier unit, and the output power is about 100mW-500mW. After that, through step-by-step amplification, a polarization-maintaining fundamental frequency pulse laser with high peak value, high energy and narrow line width is output, and the frequency is doubled by a suitable frequency doubling device 17 to obtain the required short-wavelength pulse laser, which can meet the pulse green light output with a frequency doubling efficiency of 60% at most.

[0082] In the embodiment of the present invention, the 10nm-20nm laser output by the superfluorescent semiconductor laser 11 is modulated into a narrow-band light source of 1nm-2nm for the first time, and then modulated into a narrow-band light source of 0.01nm-0.5nm for the second time, and the spectral range is gradually narrowed, so that the output pulse laser can have a narrow line width and a high side mode suppression ratio, and thus the nonlinear spectrum broadening can be suppressed as much as possible during the amplification process, and finally a narrow output spectrum can be maintained while obtaining a large pulse energy, so that it is very suitable as a fundamental frequency light source for nonlinear frequency conversion, and a more stable laser output with a higher frequency doubling efficiency is obtained, thereby improving the power and stability of short pulse lasers.

[0083] The short-wavelength pulse laser of the embodiment of the present invention has the following effects:

[0084] The embodiment of the present invention utilizes the superfluorescent semiconductor laser 11 to directly modulate and output a first pulse laser, and sequentially filters the first pulse laser through a narrowband filter 13 and a filter amplifier unit to obtain a second pulse laser and a third pulse laser with successively decreasing spectral width ranges, and finally frequency-doubles the third pulse laser through a frequency doubling device 17 to obtain a high-power short-wavelength pulse laser. The embodiment of the present invention adopts a method of directly modulating the superfluorescent semiconductor laser 11 and then filtering and amplifying it, thereby eliminating the need for manufacturing an ASE light source and an external optical modulator, and while saving costs, because direct modulation has a faster modulation rising edge and is mature, it can output a narrower pulse width, and at the same time, it can achieve high-precision waveform editing requirements, meet wider application requirements, and ultimately achieve a frequency doubling efficiency of about 60%.

[0085] By modulating the 10nm-20nm laser output by the superfluorescent semiconductor laser 11 into a narrow-band light source of 1nm-2nm for the first time, and then modulating it into a narrow-band light source in the range of 0.01nm-0.5nm for the second time, and by gradually narrowing the spectral range, the output pulse laser can have a narrow linewidth and a high side mode suppression ratio, and thus the nonlinear spectrum broadening can be suppressed as much as possible during the amplification process, and ultimately a relatively narrow output spectrum can be maintained while obtaining a large pulse energy, making it very suitable as a fundamental frequency light source for nonlinear frequency conversion, and obtaining a higher frequency doubling efficiency and more stable laser output, thereby improving the power and stability of short-pulse lasers.

[0086] Although example embodiments and their advantages have been described in detail, those skilled in the art may make various changes, substitutions and modifications to these embodiments without departing from the spirit and defined scope of the present invention, and such modifications and variations are all within the defined scope.

Claims

1. A short wavelength pulse laser, characterized in that: include: A superfluorescent semiconductor laser (11) is used for modulating and outputting a first pulse laser with a spectrum width range in a first width range; A narrowband filter (13) is used to perform narrowband filtering on the first pulse laser to obtain a second pulse laser having a spectral width range of a second width range, wherein the second width range is smaller than the first width range; a filtering and amplifying unit, configured to perform narrow-band filtering and power amplification on the second pulsed laser to obtain a third pulsed laser having a spectrum width range of a third width range, wherein the third width range is smaller than the second width range; The frequency doubling device (17) is used for frequency doubling the third pulse laser to obtain short-wavelength pulse laser.

2. The short-wavelength pulse laser according to claim 1, characterized in that: The first width ranges from 10 nm to 20 nm, the second width ranges from 1 nm to 2 nm, and the third width ranges from 0.01 nm to 0.5 nm.

3. The short-wavelength pulse laser according to claim 2, characterized in that: The central wavelength of the first laser is 1030 nm or 1064 nm.

4. The short-wavelength pulse laser according to claim 1, characterized in that: The filtering and amplifying unit comprises an optical fiber circulator (14), a first active optical fiber (21), a first wavelength division multiplexer (22), a first pump source (24) and a narrowband high-reflection grating (23); a first end of the optical fiber circulator (14) is connected to the narrowband filter (13); a second end of the optical fiber circulator (14) is connected to one end of the first active optical fiber (21); the other end of the first active optical fiber (21) is connected to the first wavelength division multiplexer (22); the first pump source (24) is used to input a first pump light into the first active optical fiber (21) through the first wavelength division multiplexer (22); the narrowband high-reflection grating (23) is used to perform narrowband filtering on the laser output by the first wavelength division multiplexer (22), and then reflect the laser back to the first wavelength division multiplexer (22), and enter the second active optical fiber through the first wavelength division multiplexer (22).

5. The short-wavelength pulse laser according to claim 1, characterized in that: The invention also comprises a first isolator (12), wherein the first isolator (12) is arranged between the superfluorescent semiconductor laser (11) and the narrowband filter (13).

6. The short-wavelength pulse laser according to claim 1, characterized in that: It also comprises a step-by-step amplifier (16), the input end of the step-by-step amplifier (16) is connected to the output end of the filtering and amplifying unit, and the output end of the step-by-step amplifier (16) is connected to the frequency multiplication device (17).

7. The short-wavelength pulse laser according to claim 6, characterized in that: The step-by-step amplifier (16) comprises a plurality of power amplifiers connected in series, each of the power amplifiers comprising a second pump source, a beam combiner and a second active optical fiber, one input end of the beam combiner is connected to the output end of the filter amplification unit, the other input end of the beam combiner is connected to the second pump source, and the output end of the beam combiner is connected to one end of the second active optical fiber.

8. The short-wavelength pulse laser according to claim 7, characterized in that: A second isolator (15) is provided between the first power amplifier and the filter amplification unit connected in series, and a third isolator is provided between each of the power amplifiers.

9. The short-wavelength pulse laser according to claim 1, characterized in that: The superfluorescent semiconductor laser (11), the narrowband filter (13), the filtering and amplifying unit, and the frequency doubling device (17) are all polarization-maintaining devices.

10. The short-wavelength pulse laser according to claim 1, characterized in that: The superfluorescent semiconductor laser (11) is a butterfly-packaged superfluorescent semiconductor laser (11).

Images