Laser amplification system

Abstract

The utility model provides a laser amplification system, relates to the technical field of optical fiber solid amplification, and aims to realize high light spot quality of an amplified light beam through solid amplification of an optical fiber seed source and edge stray light filtering of an amplified laser signal after amplification, thereby realizing output of the high-efficiency amplified and high-quality light beam.

Description

Technical Field

[0001] The present application relates to the technical field of optical fiber solid amplification, and in particular to a laser amplification system. Background Art

[0002] With the rapid development of industrial manufacturing, lasers play an increasingly important role in production and manufacturing, and at the same time, higher and higher requirements are placed on the output parameters of lasers. Due to the limitations of the nonlinear effects of fiber laser materials, high peak power laser output cannot be obtained. With the emergence of fiber-solid hybrid amplification technology, fiber lasers output high beam quality, and high-stability seeds enter solid amplification. Solid gain media can withstand high peak power pulses many times higher than optical fibers, thereby obtaining high peak power and high average power laser output.

[0003] The existing fiber-solid hybrid amplification technology requires very delicate adjustments to match the size of the seed light and the pump light in the laser crystal, which increases the difficulty of debugging. During the double-pass or single-pass laser amplification process, stray light is easily generated outside the main light spot, resulting in poor light spot quality and limiting the amplification efficiency. Utility Model Content

[0004] The laser amplification system provided in the present application achieves high quality of the spot of the amplified light beam by solid amplification of the optical fiber seed source and filtering out edge stray light of the amplified laser signal after amplification, thereby achieving output of a highly efficiently amplified and high-quality light beam.

[0005] To achieve the above purpose, the technical solution adopted in the embodiment of the present application is as follows:

[0006] In one aspect of an embodiment of the present application, a laser amplification system is provided, including an optical fiber seed source, wherein a seed laser signal emitted from the optical fiber seed source is amplified by an energy amplification unit after being amplified by an isolator and then polarized by a half-wave plate, and then emitted as an amplified laser signal. The amplification unit includes a lens, a laser crystal, a pump module, and a soft-edge aperture arranged in sequence, wherein the pump light emitted from the pump module is incident on the laser crystal for pumping, and the laser signal is modulated by the lens and incident on the laser crystal for amplification, and then filtered out as an amplified laser signal after the edge stray light is filtered out by the soft-edge aperture.

[0007] In one possible implementation of the embodiment of the present application, the amplification unit includes a double-pass pre-amplification unit and a single-pass main-amplification unit arranged in sequence along the main optical axis, the double-pass pre-amplification unit includes a first lens, a first laser crystal, a dichroic mirror and a first pump module arranged in sequence, the pump light emitted by the first pump module is incident on the first laser crystal for pumping, the seed laser signal after polarization conversion is focused by the first lens and incident on the first laser crystal for primary amplification, the seed laser signal amplified once is reflected by the dichroic mirror and incident on the first laser crystal again for secondary amplification and emission, the double-pass pre-amplification unit also includes a first soft-edge aperture arranged on one side of the first laser crystal, the laser signal amplified twice is emitted after filtering out edge stray light through the first soft-edge aperture. The single-pass main-amplification unit includes a second lens, a second laser crystal and a second pump module arranged in sequence, the pump light emitted by the second pump module is incident on the second laser crystal for pumping, the laser signal is modulated by the second lens and incident on the second laser crystal for amplification and then emitted as an amplified laser signal.

[0008] In a possible implementation manner of the embodiment of the present application, the one-way main amplifier unit also includes a second soft-edge aperture arranged on the amplified light output side of the second laser crystal, and the amplified laser signal pumped and amplified by the second laser crystal is filtered through the second soft-edge aperture to filter edge stray light.

[0009] In a possible implementation scheme of the embodiment of the present application, the two-way pre-amplifier unit includes at least one group, and / or the one-way main amplifier unit includes at least one group; when the one-way main amplifier unit includes two or more groups, the two or more groups of one-way main amplifier units are arranged on the amplification output side of at least one group of two-way pre-amplifier units.

[0010] In a possible implementation scheme of the embodiment of the present application, the double-pass pre-amplifier unit is an off-axis double-pass amplifier. A reflector is also provided in the double-pass pre-amplifier unit, through which the seed laser signal is reflected into the first laser crystal for primary amplification, and then the optical path is turned by the color separation mirror so that an off-axis angle is formed between the seed laser signal focused by the first lens and incident on the first laser crystal for primary amplification and the laser signal amplified twice by the first laser crystal and emitted.

[0011] In one possible implementation of an embodiment of the present application, a first pump module includes a first pump source and a first pump lens group arranged on the light-emitting side of the first pump source, and the pump light emitted by the first pump source is collimated and focused by the first pump lens group and then incident on the first laser crystal for pumping; a second pump module includes a second pump source and a second pump lens group arranged on the light-emitting side of the second pump source, and the pump light emitted by the second pump source is collimated and focused by the second pump lens group and then incident on the second laser crystal for pumping.

[0012] In a possible implementation manner of the embodiment of the present application, the first lens is a plano-convex lens, and the seed laser signal after polarization conversion is incident from the curved side of the plano-convex lens and is focused and emitted from the flat side.

[0013] In a possible implementation scheme of the embodiment of the present application, the second lens includes a plano-convex lens and / or a plano-concave lens, and the laser signal emitted after being amplified by a double-pass pre-amplification unit and filtering out edge stray light is incident on the second laser crystal after being modulated by the plano-convex lens and / or the plano-concave lens in terms of divergence angle and laser spot size.

[0014] In a possible implementation scheme of an embodiment of the present application, the first soft-edge aperture includes a light-transmitting area located in the central area, a transition area surrounding the periphery of the light-transmitting area, and a shielding area located outside the transition area; the transmittance of the transition area to the laser signal gradually decreases from the center to the periphery; the width of the transition area is between 0.4mm-0.6mm.

[0015] In a possible implementation of the embodiment of the present application, in the first soft-edge aperture, the ratio of the radius of the light-transmitting area to the width of the transition area is 3:1 to 8:1, and the ratio increases with the increase in the setting level of the amplification unit.

[0016] In a possible implementation scheme of the embodiment of the present application, the laser amplification system also includes an acousto-optic modulator, a cylindrical lens and an LBO frequency doubling crystal arranged on the light output side of the amplified laser signal after the amplification unit. The amplified laser signal is shaped by the cylindrical lens light spot after passing through the acousto-optic modulator, and then emitted after frequency doubling through the LBO frequency doubling crystal.

[0017] In one possible implementation of the embodiment of the present application, the optical fiber seed source is a nanosecond optical fiber seed source or a picosecond optical fiber seed source.

[0018] In another aspect of an embodiment of the present application, a laser amplification device is provided, comprising a device housing and a laser amplification system such as any one of the above-mentioned ones arranged in the device housing, wherein a light exit window is arranged on the device housing, and an amplified laser signal emitted by the laser amplification system is emitted to the outside of the device housing through the light exit window.

[0019] In a possible implementation scheme of the embodiment of the present application, the laser amplification system also includes a plurality of plane mirrors arranged at a 45° angle along the main optical axis, and the optical path of the laser signal is bent by the plane mirrors so that the double-pass pre-amplifier unit and the single-pass main-amplifier unit are arranged in parallel and spaced apart in the device housing. A water cooling mechanism is also provided in the device housing for water-cooling and circulating heat dissipation of the first laser crystal of the double-pass pre-amplifier unit and the second laser crystal of the single-pass main-amplifier unit.

[0020] The beneficial effects of the embodiments of the present application include:

[0021] The embodiment of the present application provides a laser amplification system, including an optical fiber seed source, wherein the seed laser signal emitted by the optical fiber seed source is amplified by the energy of the amplification unit after being amplified by the isolator and the half-wave plate, and then emitted as an amplified laser signal. The amplification unit includes a lens, a laser crystal, a pump module and a soft-edge aperture arranged in sequence, and the pump light emitted by the pump module is incident on the laser crystal for pumping, and the laser signal is modulated by the lens and incident on the laser crystal for amplification, and then filtered out as an amplified laser signal after the edge stray light is filtered out by the soft-edge aperture. The seed laser signal emitted by the optical fiber seed source has not been amplified and modulated and filtered, and usually has a very low power. Through the amplification of the amplification unit, more energy can be extracted from the laser crystal, so that the emitted amplified laser signal has a higher amplification efficiency. After being amplified by the laser crystal, the stray light in the emitted laser beam is separated from the periphery of the light spot, and the peripheral stray light is filtered out by the soft-edge aperture and then output, so that the emitted amplified laser signal has a higher beam quality and amplification efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 One of the optical path structure schematic diagrams of a laser amplification system provided in an embodiment of the present application;

[0024] Figure 2 A second schematic diagram of an optical path structure of a laser amplification system provided in an embodiment of the present application;

[0025] Figure 3 A third schematic diagram of the optical path structure of a laser amplification system provided in an embodiment of the present application;

[0026] Figure 4 A fourth schematic diagram of the optical path structure of a laser amplification system provided in an embodiment of the present application;

[0027] Figure 5 A fifth optical path structure diagram of a laser amplification system provided in an embodiment of the present application;

[0028] Figure 6 A schematic diagram of the structure of a first soft-edge aperture in a laser amplification system provided in an embodiment of the present application;

[0029] Figure 7 Schematic diagram of the optical path structure of a laser amplification system provided in an embodiment of the present application; six.

[0030] Icons: 3-1-amplification unit; 3-11-lens; 3-12-laser crystal; 3-13-pump module; 3-14-soft-edge aperture; 10-fiber seed source; 20-half wave plate; 30-dual-pass pre-amplification unit; 31-first lens; 32-first laser crystal; 33-dichroic mirror; 34-first pump module; 341-first pump source; 342-first pump lens group; 35-first soft-edge aperture; 40-single-pass main amplifier unit; 41-second lens; 42-second laser crystal; 43-second pump module; 431-second pump source; 432-second pump lens group; 44-second soft-edge aperture; 50-isolator; 60-acoustic-optic modulator; 70-cylindrical lens; 80-LBO frequency doubling crystal. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. It should be noted that, in the absence of conflict, the various features in the embodiments of the present application can be combined with each other, and the combined embodiments are still within the scope of protection of the present application.

[0032] In the description of the present application, 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 application and simplifying the description, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0033] In one aspect of the embodiments of the present application, a laser amplification system is provided, such as Figure 1 As shown, it includes an optical fiber seed source 10. The seed laser signal emitted by the optical fiber seed source 10 is amplified by the energy of the amplifying unit 3-1 after being amplified by the isolator 50 and the half wave plate 20. The amplified laser signal is emitted. The amplifying unit 3-1 includes a lens 3-11, a laser crystal 3-12, a pump module 3-13 and a soft-edge aperture 3-14 arranged in sequence. The pump light emitted by the pump module 3-13 is incident on the laser crystal 3-12 for pumping. The laser signal is modulated by the lens 3-11 and incident on the laser crystal 3-12 for amplification. After the edge stray light is filtered out by the soft-edge aperture 3-14, it is emitted as an amplified laser signal.

[0034] like Figure 1As shown, the optical fiber seed source 10 emits a seed laser signal, but in specific applications, the power of the seed laser signal is very small, and direct output cannot meet the application requirements. It is often necessary to pre-amplify the seed laser signal with solid state, but the output spot of the seed laser signal and the solid state pump light are difficult to match, especially in double-pass or even multi-pass amplification, and stray light is easily generated outside the output spot during the amplification process. If the stray light is not processed, in the subsequent amplification, the stray light outside the spot is easily amplified, which will cause the spot to deteriorate and affect its application.

[0035] Therefore, in the laser amplification system of the present application example, after the seed laser signal emitted by the optical fiber seed source 10 passes through the isolator 50, the half wave plate 20 polarizes the seed laser signal, and the seed laser signal is incident on the amplification unit 3-1 with vertical polarization for amplification, and then passes through the soft-edge aperture 3-14 with matching preset parameters. The soft-edge aperture 3-14 filters out the stray light ring generated on the periphery of the light spot of the seed laser signal during the amplification process of the amplification unit 3-1, and obtains a high-quality output light spot. In the solid amplification optical path, the amplified high-power laser can be isolated by the isolator 50, so as to avoid the return light or the self-laser returning to the original path and damaging the optical fiber seed source 10.

[0036] It should be noted that the specific design of the soft-edge aperture 3-24 includes first calculating the spot size of the laser signal at the laser crystal 3-12 and the approximate spot size of the pump light, using a plano-convex lens and / or a plano-concave lens to adjust the spot size and divergence angle of the laser signal at the laser crystal 3-12 so that the spot size of the laser signal matches the spot size of the pump light to increase the pump light power, and using CCD to observe the superposition relationship of the spots in real time to improve the accuracy of the adjustment. After the pump light power increases to the preset power, the stray light can be made to form a stray light ring around the main light spot.

[0037] At this time, if the high-quality output light spot needs to be further amplified, it can enter the subsequent stage for further amplification, and the peripheral stray light of the further amplified light spot can be filtered out through the soft-edge aperture 3-14, and finally a high beam quality laser can be output.

[0038] The embodiment of the present application provides a laser amplification system, including an optical fiber seed source 10. The seed laser signal emitted by the optical fiber seed source 10 is amplified by the energy of the amplification unit 3-1 after being amplified by the isolator 50 and the half-wave plate 20. The amplified laser signal is emitted. The amplification unit 3-1 includes a lens 3-11, a laser crystal 3-12, a pump module 3-13 and a soft-edge aperture 3-14 arranged in sequence. The pump light emitted by the pump module 3-13 is incident on the laser crystal 3-12 for pumping. The laser signal is modulated by the lens 3-11 and incident on the laser crystal 3-12 for amplification. The edge stray light is filtered out by the soft-edge aperture 3-14 and the amplified laser signal is emitted. The seed laser signal emitted by the optical fiber seed source 10 is not amplified and modulated and filtered, and is usually of very low power. Through the amplification of the amplification unit 3-1, more energy in the laser crystal 3-12 can be extracted, so that the emitted amplified laser signal has a higher amplification efficiency. After being amplified by the laser crystal 3-12, the stray light in the emitted laser beam is separated from the periphery of the light spot, and is output after filtering out the peripheral stray light through the soft-edge aperture 3-14, so that the emitted amplified laser signal has higher beam quality and amplification efficiency.

[0039] In one possible implementation of the present application, Figure 2 As shown, the amplification unit 3-1 includes a double-pass pre-amplification unit 30 and a single-pass main-amplification unit 40 which are sequentially arranged along the main optical axis. The double-pass pre-amplification unit 30 includes a first lens 31, a first laser crystal 32, a dichroic mirror 33 and a first pump module 34 which are sequentially arranged. The pump light emitted by the first pump module 34 is incident on the first laser crystal 32 for pumping. The seed laser signal after polarization conversion is focused by the first lens 31 and incident on the first laser crystal 32 for primary amplification. The seed laser signal amplified once is reflected by the dichroic mirror 33 and incident on the first laser crystal 32 again for secondary amplification and emission. The double-pass pre-amplification unit 30 also includes a first soft-edge aperture 35 arranged on one side of the first laser crystal 32. The laser signal emitted after secondary amplification is emitted after filtering out edge stray light through the first soft-edge aperture 35. The one-way main amplifier unit 40 includes a second lens 41, a second laser crystal 42 and a second pump module 43 which are arranged in sequence. The pump light emitted by the second pump module 43 is incident on the second laser crystal 42 for pumping. The laser signal is modulated by the second lens 41 and incident on the second laser crystal 42 for amplification and then emitted as an amplified laser signal.

[0040] Specifically, Figure 2As shown, the double-pass pre-amplifier unit 30 includes a first lens 31, a first laser crystal 32, a dichroic mirror 33 and a first pump module 34 which are arranged in sequence. The first pump module 34 emits pump light, and the wavelength and other parameters of the pump light are determined by the relevant settings of the first pump module 34. Among them, those skilled in the art should know that the wavelength selection of the pump light needs to be matched with the crystal selection, doping concentration, etc. of the first laser crystal 32 for associated setting, and no further details are given here. The pump light is incident on the first laser crystal 32 for pumping, and the vertically polarized seed laser signal first enters the double-pass pre-amplifier unit 30. After the focusing effect of the first lens 31, the spot size of the seed laser signal at the incident first laser crystal 32 is controlled and the divergence angle of the seed laser signal is increased. The seed laser signal is incident on the first laser crystal 32 with a certain divergence angle for a first amplification. The seed laser signal with a certain divergence angle can offset the spot deterioration caused by the laser wavefront distortion caused by the thermal lens effect to a certain extent.

[0041] The seed laser signal after the first amplification is reflected by the dichroic mirror 33, and the reflected seed laser signal is incident on the first laser crystal 32 for secondary amplification and emission after the divergence angle is increased by adjustment of the dichroic mirror 33. The dichroic mirror 33 can select the wavelength so that the pump light emitted by the first pump module 34 is incident on the first laser crystal 32 for pumping, and the seed laser signal after the first amplification is reflected and incident on the first laser crystal 32 again for secondary amplification and emission.

[0042] Through the double amplification of the double-pass pre-amplification unit 30, the first laser crystal 32 is fully utilized to achieve high-power pre-amplification of the seed laser signal with a compact optical path structure.

[0043] The double-pass preamplifier unit 30 also includes a first soft-edge aperture 35 disposed on one side of the first laser crystal 32. The laser signal that is amplified twice is emitted after filtering out edge stray light through the first soft-edge aperture 35. Due to the spot modulation of the seed laser signal by the first lens 31 and the dichroic mirror 33, most of the stray light in the spot of the laser signal that is amplified twice by the double-pass preamplifier unit 30 is formed into a ring that is separated from the main spot and surrounds the main spot. The first soft-edge aperture 35 is also disposed on one side of the first laser crystal 32. After the laser signal passes through the first soft-edge aperture 35, the separated ring formed by the stray light can be filtered out to output a high-quality beam laser.

[0044] After being amplified twice by the double-pass pre-amplifier unit 30 and removing stray light, the laser signal is incident on the single-pass main amplifier unit 40. Figure 2As shown, the one-way main amplifier unit 40 includes a second lens 41, a second laser crystal 42 and a second pump module 43 which are arranged in sequence. The pump light emitted by the second pump module 43 enters the second laser crystal 42 for pumping. The laser signal is first adjusted and focused by the second lens 41, and the spot size and divergence angle of the laser signal are modulated to offset the focusing effect of the second laser crystal 42 on the laser signal due to the thermal lens effect. After modulation, the laser signal is incident on the second laser crystal 42 for amplification, completing the re-amplification of the laser signal by the one-way main amplifier unit 40, so as to emit an amplified laser signal with better beam quality and larger light energy.

[0045] It should be noted that in the laser amplification system of the embodiment of the present application, the number of sets of the double-pass pre-amplifier unit 30 and the single-pass main amplifier unit 40 for hybrid amplification of the seed laser signal emitted by the optical fiber seed source 10 is not specifically limited. The double-pass pre-amplifier unit 30 and the single-pass main amplifier unit 40 can each include one or more groups. The more the number of sets, the stronger the amplification ability of the laser signal. However, it is also necessary to coordinate the design of the implementation optical path at the same time, and simultaneously consider the setting of the optical elements in the optical path during the amplification process to ensure the beam quality of the emitted amplified laser signal. Specifically, those skilled in the art can set the specific number of groups according to the specific parameter requirements of the laser application equipment for the output amplified laser signal.

[0046] In one possible implementation of the present application, Figure 3 As shown, the one-way main amplifier unit 40 also includes a second soft-edge aperture 44 arranged on the amplified light output side of the second laser crystal 42. The amplified laser signal pumped and amplified by the second laser crystal 42 is filtered through the second soft-edge aperture 44 to filter edge stray light.

[0047] like Figure 3 As shown, in the one-way main amplifier unit 40, a second soft-edge aperture 44 is further provided on the amplified light-emitting side of the second laser crystal 42. After the laser signal is adjusted and focused by the second lens 41 of the one-way main amplifier unit 40, and the spot size and divergence angle of the laser signal are adjusted to meet the preset requirements, the laser signal is amplified in the second laser crystal 42. In the amplified laser signal, stray light is generated during the amplification process because the laser signal and the pump light are not completely matched. The stray light forms a peripheral stray light ring around the main light spot again. At this time, the second soft-edge aperture 44 with appropriate parameters set on the amplified light-emitting side of the second laser crystal 42 filters the peripheral stray light ring and outputs a laser with high beam quality.

[0048] Through the combined effect of the second lens 41 and other optical elements in the optical path, the stray light is still separated in the form of a circular ring on the periphery of the main spot of the laser signal. The stray light can be filtered out by the second soft-edge aperture 44 set on the amplified light output side of the second laser crystal 42, so that a relatively clean amplified laser signal with good beam quality can be output.

[0049] In a possible implementation scheme of the embodiment of the present application, the two-way pre-amplifier unit 30 includes at least one group, and / or the one-way main amplifier unit 40 includes at least one group; when the one-way main amplifier unit 40 includes two or more groups, the two or more groups of one-way main amplifier units 40 are arranged on the amplification output side of at least one group of two-way pre-amplifier units 30.

[0050] As mentioned above, both the double-pass pre-amplifier unit 30 and the single-pass main amplifier unit 40 can be set to multiple groups in the laser amplification system of the embodiment of the present application. If two or more groups of the single-pass main amplifier unit 40 are set in the laser amplification system, then the two or more groups of the single-pass main amplifier units 40 are set on the amplification output side of at least one group of the double-pass pre-amplifier unit 30. That is to say, if two or more groups of the double-pass pre-amplifier unit 30 are set, then at least one group of the double-pass pre-amplifier unit 30 is set at the front end of the laser amplification system of the embodiment of the present application, and the optical fiber seed source 10 emits The seed laser signal first enters the front-end double-pass pre-amplifier unit 30 for double-pass energy amplification and filtering out stray light before being output from the amplified output side. The double-pass pre-amplifier unit 30 can more efficiently perform the first energy amplification on the seed laser signal emitted by the optical fiber seed source 10 to achieve the best primary amplification effect. Moreover, the optical path before the front-end double-pass pre-amplifier unit 30 is also more conducive to the arrangement and setting of optical elements such as the first lens 31 to adjust the incident posture of the seed laser signal and match it as much as possible to offset the focusing effect of the thermal lens effect. Then it enters another group or multiple groups of double-pass pre-amplifier units 30 and single-pass main amplifier units 40 for further amplification and processing to meet the parameter requirements of the required laser signal.

[0051] For example, Figure 4 As shown, the laser amplification system includes a set of double-pass pre-amplifier units 30 and two sets of single-pass main amplifier units 40, and in the optical path of the laser amplification system, the seed laser signal first passes through a set of double-pass pre-amplifier units 30 for double-pass energy amplification and filtering out the separation ring of stray light, and then passes through the two sets of single-pass main amplifier units 40 for single-pass energy amplification and stray light filtering before output.

[0052] It should be noted that, since the parameters such as the spot size and divergence angle of the laser signal incident on each stage of the two-way pre-amplifier unit 30 or each stage of the one-way main amplifier unit 40 are different, the parameters of the amplified laser signal output through the amplification effect of each stage of the two-way pre-amplifier unit 30 or each stage of the one-way main amplifier unit 40 are also different. Therefore, even if multiple groups of two-way pre-amplifier units 30 or multiple groups of one-way main amplifier units 40 are arranged in the optical path, the setting positions and parameters of the first lenses 31 in the multiple groups of two-way pre-amplifier units 30 are usually not the same, and the setting positions and parameters of the second lenses 41 in the multiple groups of one-way main amplifier units 40 are usually not the same.

[0053] In one possible implementation of the present application, Figure 2 As shown, the double-pass pre-amplifier unit 30 is an off-axis double-pass amplifier. A reflector is also provided at an appropriate position in the optical path of the double-pass pre-amplifier unit 30. The seed laser signal is reflected into the first laser crystal 32 by the reflector for primary amplification. The optical path is then turned by the color separation mirror 33 so that the seed laser signal focused by the first lens 31 and incident on the first laser crystal 32 for primary amplification forms an off-axis angle with the laser signal amplified twice by the first laser crystal 32.

[0054] In the double-pass preamplifier unit 30, due to the thermal lens effect, the laser signal is focused by the first laser crystal 32 twice in succession, which will lead to the deterioration of the laser spot when pumped at high power. Therefore, after the laser signal is amplified by the first laser crystal 32 for the first time, it is reflected by the dichroic mirror 33 and enters the first laser crystal 32 again for amplification.

[0055] It should be noted that the dichroic mirror 33 in the embodiment of the present application can be a plane dichroic mirror or a plano-convex dichroic mirror. Both sides of the plane dichroic mirror are planes. The pump light passes through the plane dichroic mirror and is incident on the first laser crystal 32 for pumping. The laser signal after the first amplification by the first laser crystal 32 is reflected by the plane dichroic mirror and is incident on the first laser crystal 32 again for secondary amplification.

[0056] If the dichroic mirror 33 in the embodiment of the present application adopts a plano-convex dichroic mirror, one side of the plano-convex dichroic mirror is flat and the other side is convex, the pump light is incident from the plane of the plano-convex dichroic mirror and emitted from the convex surface and then enters the first laser crystal 32 for pumping, and the laser signal after the first amplification by the first laser crystal 32 is reflected by the convex surface of the plano-convex dichroic mirror, and the plano-convex dichroic mirror increases the divergence angle of the laser signal during reflection, and the laser signal with the increased divergence angle is incident on the first laser crystal 32 again for secondary amplification, which offsets the focusing effect of the thermal lens on the laser signal to a certain extent, and effectively avoids the deterioration of the light spot.

[0057] like Figure 4As shown, the isolator 50 is arranged in the optical path of the laser amplification system of the embodiment of the present application. For example, the isolator 50 is arranged before the double-pass pre-amplifier unit 30. The amplified high-power laser is in the solid-state amplification optical path. The return light reflected by the surface of the component or the self-laser generated by the laser crystal 3-12 in the amplification unit 3-1 can be isolated by the isolator 50 to avoid the return light or the self-laser returning to the original path and damaging the optical fiber seed source 10.

[0058] In one possible implementation of the present application, Figure 5 As shown, the first pump module 34 includes a first pump source 341 and a first pump lens group 342 arranged on the light-emitting side of the first pump source. The pump light emitted by the first pump source 341 is collimated and focused by the first pump lens group 342 and then incident on the first laser crystal 32 for pumping; the second pump module 43 includes a second pump source 431 and a second pump lens group 432 arranged on the light-emitting side of the second pump source 431. The pump light emitted by the second pump source 431 is collimated and focused by the second pump lens group 432 and then incident on the second laser crystal 42 for pumping.

[0059] For example, Figure 5 As shown, the first pump source 341 adopts a semiconductor pump source, the first pump lens group 342 includes two pump lenses, and the pump light emitted by the semiconductor pump source is collimated and focused by the two pump lenses before being incident on the first laser crystal 32 for pumping. The second pump source 431 adopts a semiconductor pump source, the second pump lens group 432 includes two pump lenses, and the pump light emitted by the semiconductor pump source is collimated and focused by the two pump lenses before being incident on the second laser crystal 42 for pumping. Among them, the parameters such as the curvature of the two pump lenses and the positional relationship of the two pump lenses in the optical path can be specifically designed and set by those skilled in the art according to needs and in accordance with the relevant parameters of the semiconductor pump source.

[0060] In a possible implementation of the embodiment of the present application, the first lens 31 is a plano-convex lens, and the seed laser signal after polarization conversion is incident from the curved side of the plano-convex lens and is focused and emitted from the flat side.

[0061] The first lens 31 is configured as a plano-convex lens. By setting parameters such as the curvature of the plano-convex lens, the spot size of the laser signal at the first laser crystal 32 can be controlled through the plano-convex lens to match the pump light spot. At the same time, the divergence angle of the laser signal is increased, thereby offsetting the focusing effect of the thermal lens to a certain extent.

[0062] In a possible implementation scheme of the embodiment of the present application, the second lens 41 includes a plano-convex lens and / or a plano-concave lens, and the laser signal emitted after being amplified by the double-pass pre-amplification unit 30 and filtering out the edge stray light is incident on the second laser crystal 42 after being modulated by the plano-convex lens and / or the plano-concave lens in terms of divergence angle and laser spot size.

[0063] It should be noted that, in the embodiment of the present application, there is no specific limitation on the number of second lenses 41 and the parameter settings of the second lenses. The second lens 41 may be a single plano-convex lens or a plano-concave lens. Those skilled in the art should be aware that under some optical path conditions and magnification requirements, the modulation ability of a single lens on the laser spot is limited. Therefore, the second lens 41 may also include a combination of one or more plano-convex lenses and one or more plano-concave lenses. In the embodiment of the present application, there is no specific limitation on the number of second lenses 41. Those skilled in the art may set and match them according to the specific parameter requirements of the optical path design.

[0064] For example, Figure 2 As shown, the second lens 41 includes a plano-convex lens and a plano-concave lens arranged in sequence, wherein the setting direction, curvature and other parameters of the convex surface of the plano-convex lens in the optical path, the setting direction, curvature and other parameters of the concave surface of the plano-concave lens in the optical path, as well as the positional relationship between the plano-convex lens and the plano-concave lens, etc., all require technical personnel in this field to perform specific settings in coordination with other optical elements according to technical requirements.

[0065] In one possible implementation of the present application, Figure 6 As shown, the first soft-edge aperture 35 includes a light-transmitting area located in the central area, a transition area surrounding the periphery of the light-transmitting area, and a shielding area located outside the transition area.

[0066] It should be noted that the transition zone of the first soft-edge aperture 35 refers to the area between the light-transmitting area in the central area that allows the laser signal to pass completely and the outer shielding area that completely shields the laser signal, which allows part of the laser signal to pass through and blocks part of the laser signal. The transmittance of the spot in the entire light-transmitting area is super-Gaussian, and the ratio of the laser signal to the laser signal in the transition area is different at each position in the transition area. The width and order of the transition area can be set accordingly according to the size of the laser spot. Specifically, in the annular area made by the transition area, the transmittance of the laser signal gradually decreases from the center to the periphery, that is, the entire transition area gradually transitions from being completely transparent to being completely impermeable from the center to the periphery. Through this flexible transition, a sharp shielding boundary is avoided, thereby avoiding the laser signal from generating light diffraction at the sharp shielding boundary. This uncontrollable diffracted light emission also contains strong light energy, which may damage other optical components in the optical path.

[0067] For example, in the first soft-edge aperture 35, the width of the transition zone is set between 0.4mm and 0.6mm. Specifically, the width of the transition zone can be set to 0.4mm, or 0.5mm, etc. By setting the transition zone in this size range, a softer transition can be formed between the light-transmitting area and the shielding area, avoiding the generation of undesirable diffraction light, and will not significantly increase the size of the first soft-edge aperture 35 itself. In particular, due to the modulation of the laser signal before amplification by optical elements and the design of off-axis double-pass amplification in the double-pass pre-amplification unit 30, the main light spot and the peripheral stray light are separated to a certain extent in the light spot of the laser signal emitted after two pump amplifications, and the peripheral stray light is in the form of a separation ring on the periphery of the main light spot. Therefore, filtering the separation ring of the peripheral stray light with the first soft-edge aperture 35 also has a better matching effect.

[0068] In a possible implementation of the embodiment of the present application, in the first soft-edge aperture 35, the ratio of the radius of the light-transmitting area to the width of the transition area is 3:1 to 8:1, and the ratio increases with the increase in the setting level of the amplification unit 3-1.

[0069] The transition zone is set to form a relatively soft transition between the light-transmitting zone and the shielding zone to avoid the generation of bad diffracted light. Therefore, the ratio of the radius of the light-transmitting zone to the width of the transition zone is set between 3:1 and 8:1, so as to minimize the light energy loss of the laser signal spot in the process of passing through the first soft-edge aperture 35. According to the different amplification requirements of the laser amplification system for the laser signal, the amplification unit 3-1 can be set to one or more levels. For example, in the aforementioned part of the specification, a two-level solid amplification of a first-level double-pass pre-amplifier unit 30 and a first-level single-pass main amplifier unit 40 is set. Of course, the number of levels of the amplification unit 3-1 is not limited to this. As the number of levels of the amplification unit 3-1 increases, the ratio of the radius of the light-transmitting zone to the width of the transition zone is also increased in the range of 3:1 to 8:1, so as to minimize the light energy loss in this process.

[0070] In the laser method system of the embodiment of the present application, the one-way main release unit 40 in some embodiments also includes a second soft-edge aperture 44. The second soft-edge aperture 44 and the first soft-edge aperture 35 in their unit modules are both suitable for filtering out peripheral stray light from the light spot of the laser signal emitted after amplification. Therefore, the structure of the aforementioned first soft-edge aperture 35 can also be applied to the second soft-edge aperture 44.

[0071] In one possible implementation of the present application, Figure 7As shown, the laser amplification system also includes an acousto-optic modulator 60, a cylindrical lens 70 and an LBO frequency doubling crystal 80 arranged on the light output side of the amplified laser signal after the double-pass pre-amplifier unit 30 and the single-pass main amplifier unit 40. The amplified laser signal passes through the acousto-optic modulator 60, is spot-shaped by the cylindrical lens 70, and then is emitted after being frequency-doubled by the LBO frequency doubling crystal 80.

[0072] The amplified laser signal passes through the acousto-optic modulator 60, which modulates the amplified laser signal and outputs it as an intensity modulated wave carrying information. The cylindrical lens 70 shapes the light spot, and then passes through the LBO frequency doubling crystal 80 to output it.

[0073] In one possible implementation of the embodiment of the present application, the optical fiber seed source 10 is a nanosecond optical fiber seed source or a picosecond optical fiber seed source.

[0074] In another aspect of an embodiment of the present application, a laser amplification device is provided, comprising a device housing and a laser amplification system such as any one of the above-mentioned ones arranged in the device housing, wherein a light exit window is arranged on the device housing, and an amplified laser signal emitted by the laser amplification system is emitted to the outside of the device housing through the light exit window.

[0075] The laser amplification device is used to realize the desired working laser signal emitted by the laser amplification device through the structured overall setting through the parameter setting in the laser amplification device. The laser amplification device provided in the embodiment of the present application includes any of the aforementioned laser amplification systems, and also includes a device housing for accommodating the laser method system, and a light exit window is provided on the device housing, and the amplified laser signal finally emitted after amplification and modulation by the laser amplification system is emitted through the light exit window on the device housing.

[0076] In a possible implementation scheme of the embodiment of the present application, the laser amplification system also includes a plurality of plane mirrors arranged at an angle of 45° along the main optical axis, and the optical path of the laser signal is bent by the plane mirrors so that the double-pass pre-amplifier unit 30 and the single-pass main-amplifier unit 40 are arranged in parallel and spaced apart in the device housing. A water cooling mechanism is also provided in the device housing for water-cooling and circulating heat dissipation of the first laser crystal 32 of the double-pass pre-amplifier unit 30 and the second laser crystal 42 of the single-pass main-amplifier unit 40.

[0077] As a laser amplifying device that outputs a laser signal that meets processing or detection requirements after modulation, in order to be able to adapt to various processing or detection needs or scenarios, the device structure needs to be as miniaturized or diversified as possible. The miniaturized device design requires that the internal components be arranged more compactly, which may cause heat accumulation in the double-pass pre-amplifier unit 30 and the single-pass main amplifier unit 40 during operation. Therefore, in the laser amplifying device of the embodiment of the present application, the optical path is appropriately turned by using multiple plane reflectors arranged at a 45° angle along the main optical axis to better match the structure of the device housing and the requirements of the application scenario.

[0078] In the laser amplification device of the embodiment of the present application, the double-pass pre-release unit 30 and the single-pass main release unit 40 are arranged in parallel and spaced apart in the device housing, and a water cooling mechanism is correspondingly arranged for the double-pass pre-release unit 30 and the single-pass main release unit 40 arranged in parallel and spaced apart. Only one set of water cooling mechanism can be arranged to realize water cooling and heat dissipation for the first laser crystal 32 of the double-pass pre-release unit 30 and the second laser crystal 42 of the single-pass main release unit 40.

[0079] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A laser amplification system, characterized in that: It includes an optical fiber seed source, and a seed laser signal emitted by the optical fiber seed source is converted by polarization through an isolator and a half-wave plate, and then amplified by energy of an amplification unit to emit an amplified laser signal; The amplification unit includes a lens, a laser crystal, a pump module and a soft-edge aperture which are arranged in sequence. The pump light emitted by the pump module is incident on the laser crystal for pumping. After the laser signal is modulated by the lens and incident on the laser crystal for amplification, it is filtered out by the soft-edge aperture to remove edge stray light and then emitted as an amplified laser signal.

2. The laser amplification system according to claim 1, characterized in that: The amplification unit includes a double-pass pre-amplification unit and a single-pass main-amplification unit arranged in sequence along the main optical axis. The double-pass pre-amplification unit includes a first lens, a first laser crystal, a dichroic mirror and a first pump module arranged in sequence. The pump light emitted by the first pump module is incident on the first laser crystal for pumping. The seed laser signal after polarization conversion is focused by the first lens and incident on the first laser crystal for primary amplification. The seed laser signal amplified once is reflected by the dichroic mirror and incident on the first laser crystal again for secondary amplification and emission. The double-pass pre-amplification unit also includes a first soft-edge aperture arranged on one side of the first laser crystal. The laser signal emitted after secondary amplification is emitted after filtering out edge stray light through the first soft-edge aperture. The one-way main amplifier unit includes a second lens, a second laser crystal and a second pump module which are arranged in sequence. The pump light emitted by the second pump module is incident on the second laser crystal for pumping. The laser signal is modulated by the second lens and incident on the second laser crystal for amplification and then emitted as the amplified laser signal.

3. The laser amplification system according to claim 2, characterized in that: The one-way main amplifier unit also includes a second soft-edge aperture arranged on the amplified light output side of the second laser crystal, and the amplified laser signal output by pumping and amplifying the second laser crystal is filtered through the second soft-edge aperture to filter edge stray light.

4. The laser amplification system according to claim 2 or 3, characterized in that: The two-way pre-amplifier unit includes at least one group, and / or the one-way main amplifier unit includes at least one group; when the one-way main amplifier unit includes two or more groups, the two or more groups of the one-way main amplifier units are arranged on the amplification output side of at least one group of the two-way pre-amplifier units.

5. The laser amplification system according to claim 2, characterized in that: The double-pass pre-amplification unit is an off-axis double-pass amplification unit, and a reflector is also provided in the double-pass pre-amplification unit. The seed laser signal is reflected into the first laser crystal by the reflector for primary amplification, and then the optical path is turned by the color dichroic mirror so that an off-axis angle is formed between the seed laser signal focused by the first lens and incident on the first laser crystal for primary amplification and the laser signal amplified twice by the first laser crystal and emitted.

6. The laser amplification system according to claim 2, characterized in that: The first pump module includes a first pump source and a first pump lens group arranged on the light-emitting side of the first pump source, and the pump light emitted by the first pump source is collimated and focused by the first pump lens group and then incident on the first laser crystal for pumping; The second pump module includes a second pump source and a second pump lens group arranged on the light-emitting side of the second pump source. The pump light emitted by the second pump source is collimated and focused by the second pump lens group and then incident on the second laser crystal for pumping.

7. The laser amplification system according to claim 2, characterized in that: The first lens is a plano-convex lens, and the seed laser signal after polarization conversion is incident from the curved surface side of the plano-convex lens and is focused and emitted from the flat surface side.

8. The laser amplification system according to claim 2, characterized in that: The second lens includes a plano-convex lens and / or a plano-concave lens. The laser signal emitted after being amplified by the double-pass pre-amplification unit and filtering out the edge stray light is incident on the second laser crystal after being modulated by the plano-convex lens and / or the plano-concave lens in terms of divergence angle and laser spot size.

9. The laser amplification system according to claim 2, characterized in that: The first soft-edge aperture includes a light-transmitting area located in the central area, a transition area surrounding the periphery of the light-transmitting area, and a shielding area located outside the transition area; the transmittance of the laser signal in the transition area gradually decreases from the center to the periphery; the width of the transition area is between 0.4mm-0.6mm.

10. The laser amplification system according to claim 9, characterized in that: In the first soft-edge aperture, the ratio of the radius of the light-transmitting area to the width of the transition area is in a range of 3:1 to 8:1, and the ratio increases with an increase in the number of settings of the amplification unit.

11. The laser amplification system according to claim 1 or 2, characterized in that: The laser amplification system also includes an acousto-optic modulator, a cylindrical lens and an LBO frequency doubling crystal arranged on the light output side of the amplified laser signal after the amplification unit. The amplified laser signal is shaped by the cylindrical lens light spot after passing through the acousto-optic modulator, and then is emitted after being frequency-doubled by the LBO frequency doubling crystal.

12. The laser amplification system according to claim 1 or 2, characterized in that: The optical fiber seed source is a nanosecond optical fiber seed source or a picosecond optical fiber seed source.

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