CN117578175A - High-power purple crust second laser - Google Patents
High-power purple crust second laser Download PDFInfo
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- CN117578175A CN117578175A CN202311581780.9A CN202311581780A CN117578175A CN 117578175 A CN117578175 A CN 117578175A CN 202311581780 A CN202311581780 A CN 202311581780A CN 117578175 A CN117578175 A CN 117578175A
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- 239000013078 crystal Substances 0.000 claims abstract description 124
- 230000003321 amplification Effects 0.000 claims description 107
- 238000003199 nucleic acid amplification method Methods 0.000 claims description 107
- 230000003287 optical effect Effects 0.000 claims description 101
- 238000005086 pumping Methods 0.000 claims description 25
- 230000010287 polarization Effects 0.000 claims description 24
- 238000006243 chemical reaction Methods 0.000 claims description 23
- 230000008878 coupling Effects 0.000 claims description 20
- 238000010168 coupling process Methods 0.000 claims description 20
- 238000005859 coupling reaction Methods 0.000 claims description 20
- 229910009372 YVO4 Inorganic materials 0.000 claims description 7
- 238000000034 method Methods 0.000 abstract description 16
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- 238000005516 engineering process Methods 0.000 description 6
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- 238000005459 micromachining Methods 0.000 description 3
- 230000033228 biological regulation Effects 0.000 description 2
- 238000009776 industrial production Methods 0.000 description 2
- 230000002401 inhibitory effect Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
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- 229910052594 sapphire Inorganic materials 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/11—Mode locking; Q-switching; Other giant-pulse techniques, e.g. cavity dumping
- H01S3/1123—Q-switching
- H01S3/117—Q-switching using intracavity acousto-optic devices
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
- H01S3/08—Construction or shape of optical resonators or components thereof
- H01S3/08018—Mode suppression
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Abstract
The invention relates to the technical field of laser, and discloses a high-power ultraviolet skin second laser, which is characterized in that a multi-stage amplifying light path is arranged to amplify signal light emitted by a picosecond seed source in multiple stages, and the light path structure of a double-pass amplifying light path in the multi-stage amplifying light path is reasonably limited, namely, the incident end face of a laser crystal is limited to intersect with the signal light of the incident laser crystal at a preset inclined angle, so that the end face of the laser crystal is not parallel to a high-reflection mirror, self-oscillation is difficult to generate, the generation of self-light in the double-pass amplifying process is inhibited, and a dichroic mirror is utilized to fold the light path to stretch the distance from the laser crystal to a 0-degree reflection mirror, so that the generation of the self-light in the double-pass amplifying process is further inhibited, and the output of high-power and high-quality signal light is ensured.
Description
Technical Field
The invention relates to the technical field of lasers, in particular to a high-power ultraviolet skin second laser.
Background
The picosecond laser is a picosecond laser with the characteristics of picosecond ultra-short pulse width, adjustable repetition frequency, high pulse energy and the like, wherein ultraviolet band (355 nm band) can output shorter wavelength and higher photon energy compared with traditional infrared band (1064 nm band) and green light band (532 nm band). Therefore, the main process application of the ultraviolet skin second laser comprises micromachining of fragile materials such as sapphire, glass and ceramic, fine molding of superhard materials and micromachining of flexible PCB (printed circuit board), and can fully solve the micromachining bottleneck of industries such as panel display, photovoltaics and semiconductors.
The ultraviolet lasers on the market at present mainly comprise two types, namely a nanosecond Q-switched laser adopting intracavity frequency multiplication and a picosecond mode-locked laser adopting extracavity frequency multiplication, and compared with the picosecond mode-locked laser adopting extracavity frequency multiplication, the ultraviolet lasers mainly comprise a seed source stable mode-locked technology, a multistage and multipass solid amplification technology, a nonlinear frequency conversion technology and the like.
If the output of the high-power ultraviolet second laser is obtained, the output power of the fundamental frequency light (infrared) needs to be improved, and meanwhile, the good beam quality needs to be maintained. The picosecond light source directly generated by the oscillator is difficult to directly apply to industrial production due to low power and small single pulse energy, so that the power amplification of the signal light is required, and the current industry commonly uses end-pumped blocky crystals to build a multistage amplification system. The pulse energy detector has the characteristics of low cost, simple structure, reliability and capability of bearing high pulse energy. However, the inherent structure of the existing two-pass amplification generates a small amount of self-laser light and interferes with the signal light, thereby affecting the amplification efficiency and beam quality of the signal light.
Disclosure of Invention
The invention provides a high-power ultraviolet second laser, which solves the technical problems that the prior double-pass amplification inherent structure in the ultraviolet second laser can generate a small amount of self-laser and interfere signal light, thereby influencing the amplification efficiency and the light beam quality of the signal light.
In view of this, a first aspect of the present invention provides a high power uv skin second laser comprising:
a picosecond seed source 1, a multistage amplification optical path 2 and a frequency conversion optical path 3;
the picosecond seed source 1 is used for emitting signal light to the multistage amplification light path 2;
the multistage amplification light path 2 is used for carrying out multistage amplification on the signal light;
wherein the multi-stage amplification optical path 2 at least comprises a one-stage double-pass amplification optical path;
the double-pass amplifying optical path comprises a pumping component 10, a polarization isolator 11, a focusing lens 12, a laser crystal 13, a dichroic mirror 14 and a 0-degree reflecting mirror 15 which are sequentially arranged along the optical axis direction;
the pump assembly 10 is configured to provide pump light and emit the pump light to be incident on the laser crystal 13 through the dichroic mirror 14;
the signal light sequentially passes through the polarization isolator 11, the focusing lens 12 and the laser crystal 13, is reflected to the 0-degree reflecting mirror 15 through the dichroic mirror 14, is sequentially reflected back to the laser crystal 13 through the 0-degree reflecting mirror 15 and the dichroic mirror 14, and is sequentially emitted to a next-stage amplifying light path or the frequency conversion light path 3 through the laser crystal 13, the focusing lens 12 and the polarization isolator 11;
intersecting the signal light incident on the laser crystal 13 at a preset inclined angle by defining an incident end face of the laser crystal 13;
the frequency conversion optical path 3 is used for performing frequency conversion on the signal light subjected to multistage amplification by the multistage amplification optical path 2 and outputting ultraviolet band signal light.
Optionally, the multi-stage amplifying optical path 2 includes a first-stage double-pass amplifying optical path, a second-stage double-pass amplifying optical path, a third-stage single-pass amplifying optical path and a fourth-stage single-pass amplifying optical path which are sequentially arranged.
Optionally, the 0 degree mirror 15 is provided at the focal point of the thermal lens generated by the laser crystal 13.
Optionally, the high-power ultraviolet skin second laser further comprises a folded optical path, wherein the folded optical path comprises a plurality of 45-degree reflectors which are sequentially arranged, and the folded optical path is used for carrying out optical path folding on the signal light.
Optionally, the dichroic mirror 14 is a 45 degree dichroic mirror.
Alternatively, the laser crystal 13 is made of Nd: YVO4 with a doping concentration of 0.3%, and the incident end face of the laser crystal 13 has a wedge angle of 1-2 degrees.
Optionally, the high power uv skin second laser further comprises: and the acousto-optic modulator is arranged on an optical axis between the first-stage double-pass amplification optical path and the second-stage double-pass amplification optical path and is used for carrying out diffraction and light splitting on the signal light.
Optionally, the third stage single pass amplification optical path and the fourth stage single pass amplification optical path both employ single pass amplification optical paths;
the single-pass amplification optical path comprises a pumping component 20, a laser crystal 21 and a dichroic mirror 22 which are sequentially arranged;
the pump assembly 20 is configured to provide pump light and emit the pump light to be incident on the laser crystal 21 through the dichroic mirror 22;
the signal light passes through the laser crystal 21 to the dichroic mirror 22, and is reflected out through the dichroic mirror 22.
Alternatively, the laser crystal 21 is made of Nd: YVO4 having a doping concentration of 0.27%.
Optionally, the frequency conversion optical path 3 includes a coupling lens 31, a coupling lens 32, a frequency doubling crystal 33, and a frequency doubling crystal 34, which are sequentially arranged;
adjusting the spot size and divergence angle of the signal light by limiting the relative positions of the coupling lens 31 and the coupling lens 32;
the frequency doubling crystal 33 is used for frequency doubling the signal light to generate green light with 532nm wave band;
the frequency doubling crystal 34 is used for summing the signal light and the green light with the 532nm wave band and generating ultraviolet light with the 355nm wave band for output.
From the above technical scheme, the invention has the following advantages:
the invention carries out multistage amplification on the signal light emitted by the picosecond seed source by arranging the multistage amplification light path, reasonably limits the light path structure of the double-pass amplification light path in the multistage amplification light path, namely, limits the incident end face of the laser crystal to intersect the signal light of the incident laser crystal at a preset inclined included angle, so that the end face of the laser crystal is not parallel to the high-reflection mirror, thereby being difficult to generate self-excited oscillation, inhibiting the generation of the self-excited light in the double-pass amplification process, and utilizing the dichroic mirror to fold the light path to stretch the distance from the laser crystal to the 0-degree reflection mirror, thereby further inhibiting the generation of the self-excited light in the double-pass amplification process, and ensuring the output of high-power and high-quality signal light.
Drawings
Fig. 1 is a schematic structural diagram of a high-power uv-skin second laser according to a first embodiment of the present invention;
FIG. 2 is a schematic diagram of a two-pass amplifying optical path according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of the positional relationship between the end face of the laser crystal and the high-reflection mirror according to the embodiment of the present invention;
FIG. 4 is a diagram of a frequency translating optical path according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of a frequency doubling process according to an embodiment of the present invention;
FIG. 6 is a schematic diagram of a sum frequency process provided by an embodiment of the present invention;
FIG. 7 is a schematic diagram of a high power UV sheath second laser according to a second embodiment of the invention;
FIG. 8 is an optical path diagram of a single pass amplified optical path provided by an embodiment of the present invention;
fig. 9 is an optical path diagram of a high power uv sheath second laser according to a second embodiment of the present invention.
The reference numerals are explained as follows:
1: a picosecond seed source; 2: a multi-stage amplifying optical path;
3: a frequency conversion optical path; 10. 20: and (3) a pumping assembly:
11: a polarization isolator; 12: a focusing lens;
13. 21: a laser crystal; 14. 22: a dichroic mirror;
15: a 0 degree mirror; m1: a high reflection mirror;
31. 32: a coupling lens; 33. 34: a frequency doubling crystal;
3-1: a collimating lens; 1-1: a first pump assembly;
4-1: a first polarization isolator; 5-1, 5-2, 5-3, 5-4, 5-5, 5-6, 5-7, 5-8, 5-9, 5-10, 5-11, 5-12, 5-13: a 45 degree mirror;
3-2: a first focusing lens; 6-1: a first laser crystal;
7-1: a first dichroic mirror; 8-1: a first 0 degree mirror;
9: an acousto-optic modulator; 1-2: a second pump assembly;
4-2: a second polarization isolator; 3-3: a second focusing lens;
6-2: a second laser crystal; 7-2: a second dichroic mirror;
8-2: a second 0 degree mirror; 1-3: a third pump assembly;
6-3: a third laser crystal; 7-3: a third dichroic mirror;
1-4: a fourth pump assembly; 6-4: a fourth laser crystal;
7-4: a fourth dichroic mirror; 3-4, 3-5: a coupling lens;
10-1: a first frequency doubling crystal; 10-2: second frequency doubling crystal
Detailed Description
In order to make the present invention better understood by those skilled in the art, the following description will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The ultraviolet lasers on the market at present mainly comprise two types, namely a nanosecond Q-switched laser adopting intracavity frequency multiplication and a picosecond mode-locked laser adopting extracavity frequency multiplication, and compared with the picosecond mode-locked laser adopting extracavity frequency multiplication, the ultraviolet lasers mainly comprise a seed source stable mode-locked technology, a multistage and multipass solid amplification technology, a nonlinear frequency conversion technology and the like.
If the output of the high-power ultraviolet second laser is obtained, the output power of the fundamental frequency light (infrared) needs to be improved, and meanwhile, the good beam quality needs to be maintained. The picosecond light source directly generated by the oscillator is difficult to directly apply to industrial production due to low power and small single pulse energy, so that the power amplification of the signal light is required, and the current industry commonly uses end-pumped blocky crystals to build a multistage amplification system. The pulse energy detector has the characteristics of low cost, simple structure, reliability and capability of bearing high pulse energy. However, the inherent structure of the existing two-pass amplification generates a small amount of self-laser light and interferes with the signal light, thereby affecting the amplification efficiency and beam quality of the signal light.
Therefore, the high-power ultraviolet skin second laser solves the technical problems. Referring to fig. 1, fig. 1 illustrates a structure of a high-power uv-vis laser according to a first embodiment of the present invention, and the high-power uv-vis laser according to the present invention includes:
a picosecond seed source 1, a multistage amplification optical path 2 and a frequency conversion optical path 3;
the picosecond seed source 1 is used for emitting signal light to the multistage amplification light path 2;
the multi-stage amplification light path 2 is used for carrying out multi-stage amplification on the signal light;
the multi-stage amplifying optical path 2 at least comprises a one-stage double-pass amplifying optical path.
In practical application, the multi-stage amplifying optical path may be set as a one-stage amplifying optical path, a two-stage amplifying optical path, a three-stage amplifying optical path, a four-stage amplifying optical path, or the like according to the requirement of the amplification factor, which is not limited herein.
As shown in fig. 2, fig. 2 illustrates an optical path diagram of a two-way amplifying optical path including a pump assembly 10, and a polarization isolator 11, a focusing lens 12, a laser crystal 13, a dichroic mirror 14, and a 0-degree mirror 15, which are sequentially disposed in the optical axis direction;
the pump assembly 10 is used for providing pump light and emitting the pump light to be incident to the laser crystal 13 through the dichroic mirror 14;
wherein pump sources of different pump wavelengths can be used for providing pump light for providing excitation for the laser crystal 13 for all pump components in the multistage amplification optical path 2, the pump wavelengths can be determined by absorption lines of active particles of the laser crystal, such as 808nm, 880nm and 888nm, wherein the longer the pump wavelength is, the lower the pump absorption efficiency is, but the smaller the thermal effect is, so that the thermal lens effect is suppressed and the laser output power is improved by limiting the divergence wavelength of the pump sources.
The signal light sequentially passes through the polarization isolator 11, the focusing lens 12 and the laser crystal 13, is reflected to the 0-degree reflecting mirror 15 through the dichroic mirror 14, is sequentially reflected to the laser crystal 13 through the 0-degree reflecting mirror 15 and the dichroic mirror 14 in the original path, and is sequentially emitted to the next-stage amplifying light path or the frequency conversion light path through the laser crystal 13, the focusing lens 12 and the polarization isolator 11.
The engineering of the signal light entering the double-pass amplifying light path is as follows: the signal light enters the polarization isolator 11, the polarization isolator 11 transmits the signal light incident by the seed source, isolates the signal light amplified by the double-pass amplifying light path, focuses by the focusing lens 12, the focused signal light enters the laser crystal 13 to complete first amplification, then the first amplified signal light is reflected by the dichroic mirror 14 and the 0-degree reflecting mirror 15, returns to the laser crystal 13 to conduct second amplification, and then sequentially passes through the laser crystal 13, the focusing lens 12 and the polarization isolator 11 to be emitted to a next-stage amplifying light path or a frequency conversion light path, so that the signal light completes first-stage double-pass amplification, and the amplification efficiency is increased.
It should be noted that, due to the low absorption efficiency of the laser crystal 13, part of the pump light cannot be absorbed completely, resulting in low amplification efficiency. Through design, the optical path distinction is realized through the polarization isolator 11 in the double-pass amplification, the average power of the signal light can be improved by about 50%, the beam quality is kept unchanged, the comparison results of the double-pass amplification and the single-pass amplification are shown in the table 1 under the same pumping condition, the table 1 shows that the average power of the output of the two-pass amplification can be improved by about 50% on the premise that the roundness of the light spot is ensured, the corresponding self-excitation proportion is also improved by 3.5%, and meanwhile, the proportion of the self-excitation light in the double-pass amplification optical path can be restrained within 10% through the structural design of the embodiment, so that the requirement of industrial application is met.
TABLE 1
The dichroic mirror 14 may be a laser high-reflection pump high-transmission dichroic mirror, and the dichroic mirror 14 may be a 45-degree dichroic mirror.
It was found by study that the power from the laser light was smaller as the 0 degree mirror 15 was further away from the laser crystal 13 at the same pump power. Based on this, the present embodiment adopts a combination of 45-degree dichroic mirror and 0-degree reflecting mirror, and compared with the 0-degree laser high-reflection pumping light high-transmission dichroic mirror in the prior art, the distance from the laser crystal 13 to the 0-degree reflecting mirror 15 can be as far as possible, so that the generation of laser light in the double-pass amplification process can be suppressed.
In order to reduce the generation of self-laser light caused by double-pass amplification, the position of the 0-degree reflecting mirror 15 may be defined, and as a preferred scheme, the 0-degree reflecting mirror 15 is arranged at the focus of the thermal lens generated by the laser crystal 13, so that the generation of self-laser light is reduced, and the amplification efficiency of back reflection can be improved.
It should be noted that, because the pump light spot size is smaller and the gain is extremely high, under higher pump power, the resonator is easily formed by the end face of the laser crystal and the high-reflection mirror (in this embodiment, the high-reflection mirror is a flat cavity formed by the dichroic mirror 14) to generate self-oscillation, and the generation of self-oscillation will cause difficulty in obtaining gain when the signal light is input, and the self-oscillation in the first-stage double-pass amplification process will be continuously amplified in the next-stage laser amplification process, affecting the stability of the laser output, so the self-oscillation generated due to the high gain must be suppressed.
In the present embodiment, the incident end face of the laser crystal 13 is defined to intersect the signal light incident on the laser crystal 13 at a predetermined inclined angle.
As shown in fig. 3, fig. 3 illustrates a positional relationship between the end face of the laser crystal 13 and the high-reflection mirror M1, and if the resonant cavity is capable of generating laser oscillation output, the two cavity mirrors are required to be parallel to each other, so that when the end face of the laser crystal 13 and the high-reflection mirror M1 are no longer parallel, self-oscillation is more difficult to generate. In this embodiment, by limiting the incident end face of the laser crystal 13 to intersect the signal light of the incident laser crystal 13 at a preset inclined angle (greater than 0 degrees), the incident signal light forms a certain angle with the laser crystal 13, and the high-reflection mirror M1 must be perpendicular to the laser beam in order to ensure that the laser beam returns to the gain region in the original path, so that a certain angle must exist between the high-reflection mirror M1 and the end face of the laser crystal 13, thereby suppressing self-oscillation.
The frequency conversion optical path is used for carrying out frequency conversion on the signal light which is subjected to multistage amplification by the multistage amplification optical path and outputting ultraviolet band signal light.
As shown in fig. 4, fig. 4 illustrates an optical path diagram of a frequency conversion optical path including a coupling lens 31, a coupling lens 32, a frequency doubling crystal 33, and a frequency doubling crystal 34, which are sequentially arranged;
the spot size and divergence angle of the signal light are adjusted by restricting the relative positions of the coupling lens 31 and the coupling lens 32.
In the frequency multiplication process, after the frequency multiplication crystal and the length are confirmed, the main factor affecting the frequency multiplication efficiency is the peak power density of the incident laser. The collimation divergence of the beam also affects the conversion efficiency when phase mismatch is considered. In this embodiment, the focal lengths of the coupling lens 31 and the coupling lens 32 are different, and the spot size and the divergence angle of the signal light can be adjusted by limiting the relative positions of the coupling lens 31 and the coupling lens 32, so as to determine the peak power density of the incident laser, which has higher adjustment accuracy compared with the case of using a single focusing lens, and at the same time, the frequency doubling efficiency can be improved by using the dual-lens structure.
The frequency doubling crystal 33 is used for frequency doubling the signal light to generate green light of 532nm band.
The frequency doubling crystal 34 is used for summing the signal light and the green light in the 532nm wave band and generating ultraviolet light in the 355nm wave band for output.
It should be noted that, the multi-stage amplification can output fundamental frequency light with high power and high beam quality in 1064nm band, and the frequency doubling crystal adopted in the embodiment can be an LBO crystal, and is used for I-type non-critical phase matching, i.e. the temperature needs to be precisely optimized. The temperature is optimized by adopting a high-precision TEC temperature control system, so that final temperature matching is realized. The fundamental frequency light is multiplied by the frequency multiplication crystal 33 to generate green light with 532nm wave band, and then the fundamental frequency light and the green light with 532nm wave band are subjected to frequency summation by the frequency multiplication crystal 34 to generate ultraviolet light with 355nm wave band for output, wherein the principle of the frequency summation process is shown in fig. 5, the principle of the frequency summation process is shown in fig. 6, w1 represents the fundamental frequency light, w2 represents the green light with 532nm wave band, and w represents the ultraviolet light with 355nm wave band after frequency summation.
In this embodiment, the multistage amplification optical path is set to amplify the signal light emitted by the picosecond seed source, and the optical path structure of the double-pass amplification optical path in the multistage amplification optical path is defined reasonably, that is, the incident end face of the laser crystal is defined to intersect the signal light of the incident laser crystal at a preset inclined angle, so that the end face of the laser crystal is not parallel to the high-reflection mirror, and therefore self-oscillation is difficult to generate, the generation of laser in the double-pass amplification process is inhibited, and the dichroic mirror is utilized to fold the optical path to stretch the distance from the laser crystal to the 0-degree reflection mirror, so that the generation of laser in the double-pass amplification process is further inhibited, and the output of high-power and high-quality signal light is ensured.
In one implementation, the high power uv sheath second laser further includes a folded optical path including a plurality of 45 degree mirrors disposed in sequence, the folded optical path being configured to perform optical path folding on the signal light.
In one implementation, the high power uv skin second laser further comprises: the acousto-optic modulator is arranged on an optical axis between the first-stage double-pass amplification optical path and the second-stage double-pass amplification optical path and is used for carrying out diffraction and light splitting on the signal light.
The acousto-optic modulator is used for realizing regulation and control of signal light, and regulation and control parameters comprise power and repetition frequency.
The following is a detailed description of a second embodiment of the high power violet skin second laser provided by the present invention.
As shown in fig. 7, fig. 7 illustrates the structure of a high-power violet skin second laser according to a second embodiment of the present invention, which is modified from the previous embodiment, in which the multi-stage amplification optical path includes a first-stage double-pass amplification optical path, a second-stage double-pass amplification optical path, a third-stage single-pass amplification optical path, and a fourth-stage single-pass amplification optical path, which are sequentially arranged.
Wherein, the third stage single-pass amplification optical path and the fourth stage single-pass amplification optical path both adopt single-pass amplification optical paths;
as shown in fig. 8, fig. 8 illustrates an optical path diagram of a single-pass amplification optical path including a pump assembly 20, and a laser crystal 21 and a dichroic mirror 22 disposed in this order;
the pump assembly 20 is used for providing pump light and emitting the pump light to be incident on the laser crystal 21 through the dichroic mirror 22.
The signal light passes through the laser crystal 21 to the dichroic mirror 22, and is reflected out through the dichroic mirror 22.
It can be understood that the power amplification with higher power can be obtained by performing the double pass amplification twice and then performing the single pass amplification twice. Specifically, the amplifying process of the single-pass amplifying light path is as follows: the signal light enters the laser crystal 21 for amplification through the folded light path, and then is reflected to the next stage of single-pass amplification light path through the dichroic mirror 22, so that the two stages of single-pass amplification are completed, and the signal light output with high power and high beam quality is obtained.
As a preferred embodiment, as shown in fig. 9, fig. 9 illustrates an optical path diagram of the high-power ultraviolet second laser provided in this embodiment, where the high-power ultraviolet second laser includes a picosecond seed source 1, a collimating lens 3-1, a first-stage double-pass amplifying optical path, an acousto-optic modulator 9, a second-stage double-pass amplifying optical path, a third-stage single-pass amplifying optical path, a fourth-stage single-pass amplifying optical path, and a frequency conversion optical path, which are sequentially arranged;
the picosecond seed source 1 emits signal light to enter a first-stage double-pass amplifying light path through a collimating lens 3-1, wherein the first-stage double-pass amplifying light path comprises a first pumping component 1-1, and a first polarization isolator 4-1, two 45-degree reflectors 5-1 and 5-2, a first focusing lens 3-2, a first laser crystal 6-1, a first dichroic mirror 7-1 and a first 0-degree reflector 8-1 are sequentially arranged;
wherein the first pumping component 1-1 provides pumping light to enter the first laser crystal 6-1 through the first dichroic mirror 7-1;
after passing through the first polarization isolator 4-1, the signal light is reflected to the first focusing lens 3-2 through the two 45-degree reflectors 5-1 and 5-2, focused by the first focusing lens 3-2 and enters the first laser crystal 6-1 for first amplification, the signal light after the first amplification is reflected to the first 0-degree reflector 8-1 through the first dichroic mirror 7-1, is reflected again through the first 0-degree reflector 8-1 and returns to the first laser crystal 6-1 in the original path for second amplification, so that the signal light is amplified in a double-path manner, enters the first polarization isolator 4-1 through the first focusing lens 3-2, the two 45-degree reflectors 5-2 and 5-1 in sequence, and is reflected to the acousto-optic modulator 9 through the first polarization isolator 4-1 and the 45-degree reflector 5-3;
the acousto-optic modulator 9 diffracts and splits the signal light, the signal light after the diffraction and splitting is reflected to a second-stage double-pass amplifying light path through a 45-degree reflecting mirror 5-4, the second-stage double-pass amplifying light path comprises a second pumping component 1-2, and a second polarization isolator 4-2, a 45-degree reflecting mirror 5-5, a second focusing lens 3-3, a second laser crystal 6-2, a second dichroic mirror 7-2 and a second 0-degree reflecting mirror 8-2 are sequentially arranged;
wherein the second pumping component 1-2 provides pumping light to enter the second laser crystal 6-2 through the second dichroic mirror 7-2;
the signal light is reflected to the second focusing lens 3-3 through the 45-degree reflecting mirror 5-5 for focusing after passing through the second polarization isolator 4-2, the focused signal light enters the second laser crystal 6-2 for first amplification, the signal light after the first amplification is reflected to the second 0-degree reflecting mirror 8-2 through the second dichroic mirror 7-2, is reflected again through the second 0-degree reflecting mirror 8-2 and returns to the second laser crystal 6-2 in the original path for second amplification, the signal light is amplified in a double-path mode, and then enters the second polarization isolator 4-2 through the second focusing lens 3-3 and the 45-degree reflecting mirror 5-5 in sequence, and then is reflected to the third-stage single-path amplification light path through the second polarization isolator 4-2 through the two 45-degree reflecting mirrors 5-6 and 5-7;
the third-stage single-pass amplification optical path comprises a third pumping component 1-3, a third laser crystal 6-3 and a third dichroic mirror 7-3 which are sequentially arranged;
the third pumping component 1-3 provides pumping light to enter the third laser crystal 6-3 through the third dichroic mirror 7-3;
the signal light is amplified by a third laser crystal 6-3, and the amplified signal light is reflected to a fourth-stage single-pass amplifying light path by a third dichroic mirror 7-3 and three 45-degree reflecting mirrors 5-8, 5-9 and 5-10 in sequence;
the fourth-stage single-pass amplification optical path comprises a fourth pumping component 1-4, a fourth laser crystal 6-4 and a fourth dichroic mirror 7-4 which are sequentially arranged;
the fourth pumping component 1-4 provides pumping light to enter the fourth laser crystal 6-4 through the fourth dichroic mirror 7-4;
the signal light is amplified by a fourth laser crystal 6-4, and the amplified signal light is reflected to a frequency conversion light path by a fourth dichroic mirror 7-4 and a 45-degree reflecting mirror 5-11 in sequence;
the frequency conversion light path comprises two coupling lenses 3-4, 3-5, 45-degree reflecting mirrors 5-12, a first frequency doubling crystal 10-1 and a second frequency doubling crystal 10-2 which are sequentially arranged;
after the signal light is coupled through the two coupling lenses 3-4 and 3-5 in sequence, the signal light is multiplied by frequency by the first frequency doubling crystal 10-1 through the 45-degree reflecting mirror 5-12 to generate 532 nm-band frequency doubling light (infrared light), then the frequency doubling light is summed through the second frequency doubling crystal 10-2 to generate 355nm ultraviolet second laser, and 355nm ultraviolet second laser is reflected and output through the 45-degree reflecting mirror 5-13.
Wherein, the 45-degree reflector 5-13 coating film is 1064nm/532nm high-transmittance and 355nm high-reflectance.
It should be noted that, as the amplification level increases, the thermal lens effect generated by the bulk laser crystal itself may cause the spot distortion, so that the output spot mode is degraded, and the power is difficult to further increase. For this purpose, the invention defines the laser crystal in each stage of amplifying light path in the two embodiments, namely, nd: YVO4 with different doping concentrations is selected to manufacture the laser crystal, and the doping concentration ranges from 0.27% to 0.5%. The doping concentration is too low, so that the extraction efficiency of the pump is reduced, and energy loss is caused; conversely, too high a doping concentration can produce a severe thermal lens effect.
As a preferred embodiment, in the double-pass amplifying optical path, the laser crystal 13 is made of Nd: YVO4 with doping concentration of 0.3%, and the incident end face of the laser crystal 13 has a wedge angle of 1-2 degrees. In the single pass amplified light path, the laser crystal 21 was made of Nd: YVO4 with a doping concentration of 0.27%.
Meanwhile, the dimensions of the laser crystal 13 and the laser crystal 21 may be limited, and as a preferred embodiment, the dimensions of the laser crystal 13 may be 4×4×20mm, and the dimensions of the laser crystal 21 may be 3×3×30mm, so as to reduce the doping concentration of the active particles, increase the length of the laser crystal may reduce the thermal lens effect, and further improve the quality of the single-pass amplified light beam.
The above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims (10)
1. A high power uv sheath second laser, comprising:
a picosecond seed source (1), a multistage amplification optical path (2) and a frequency conversion optical path (3);
the picosecond seed source (1) is used for emitting signal light to the multistage amplification light path (2);
the multistage amplification light path (2) is used for carrying out multistage amplification on the signal light;
wherein the multistage amplification light path (2) at least comprises a one-stage double-pass amplification light path;
the double-pass amplifying light path comprises a pumping component (10), a polarization isolator (11), a focusing lens (12), a laser crystal (13), a dichroic mirror (14) and a 0-degree reflecting mirror (15) which are sequentially arranged along the optical axis direction;
the pumping component (10) is used for providing pumping light and emitting the pumping light to be incident to the laser crystal (13) through the dichroic mirror (14);
the signal light sequentially passes through the polarization isolator (11), the focusing lens (12) and the laser crystal (13), is reflected to the 0-degree reflecting mirror (15) through the dichroic mirror (14), is sequentially reflected back to the laser crystal (13) through the 0-degree reflecting mirror (15) and the dichroic mirror (14) in the original way, and sequentially passes through the laser crystal (13), the focusing lens (12) and the polarization isolator (11) to be emitted to a next-stage amplifying light path or the frequency conversion light path (3);
intersecting the signal light incident on the laser crystal (13) at a preset inclined angle by limiting the incident end face of the laser crystal (13);
the frequency conversion optical path (3) is used for carrying out frequency conversion on the signal light subjected to multistage amplification by the multistage amplification optical path (2) and outputting ultraviolet band signal light.
2. The high power uv sheath second laser of claim 1, wherein the multi-stage amplification optical path (2) comprises a first stage double-pass amplification optical path, a second stage double-pass amplification optical path, a third stage single-pass amplification optical path, and a fourth stage single-pass amplification optical path, which are sequentially arranged.
3. The high power uv sheath second laser according to claim 1, characterized in that the 0 degree mirror (15) is provided at the focal point of the thermal lens generated by the laser crystal (13).
4. The high power uv sheath second laser of claim 1, further comprising a folded optical path comprising a plurality of 45 degree mirrors disposed in sequence, the folded optical path configured to optically fold the signal light.
5. The high power uv sheath second laser of claim 1, wherein the dichroic mirror (14) is a 45 degree dichroic mirror.
6. The high power violet skin second laser according to claim 1, characterized in that the laser crystal (13) is made of Nd: YVO4 with a doping concentration of 0.3%, the incident end face of the laser crystal (13) having a wedge angle of 1-2 degrees.
7. The high power uv sheath second laser of claim 2, further comprising: and the acousto-optic modulator is arranged on an optical axis between the first-stage double-pass amplification optical path and the second-stage double-pass amplification optical path and is used for carrying out diffraction and light splitting on the signal light.
8. The high power violet sheath second laser of claim 2, wherein the third stage single pass amplification optical path and the fourth stage single pass amplification optical path each employ a single pass amplification optical path;
the single-pass amplification optical path comprises a pumping component (20), and a laser crystal (21) and a dichroic mirror (22) which are sequentially arranged;
the pumping component (20) is used for providing pumping light and emitting the pumping light to be incident to the laser crystal (21) through the dichroic mirror (22);
the signal light passes through the laser crystal (21) to the dichroic mirror (22), and is reflected out through the dichroic mirror (22).
9. The high power violet skin second laser according to claim 8, characterized in that said laser crystal (21) is made of Nd: YVO4 with a doping concentration of 0.27%.
10. The high-power ultraviolet sheath second laser according to claim 1, wherein the frequency conversion optical path (3) includes a coupling lens (31), a coupling lens (32), a frequency doubling crystal (33) and a frequency doubling crystal (34) which are sequentially arranged;
adjusting the spot size and divergence angle of the signal light by limiting the relative positions of the coupling lens (31) and the coupling lens (32);
the frequency doubling crystal (33) is used for carrying out frequency doubling on the signal light to generate green light with 532nm wave band;
the frequency doubling crystal (34) is used for carrying out frequency summation on the signal light and the green light with the 532nm wave band and generating ultraviolet light with the 355nm wave band for output.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202311581780.9A CN117578175A (en) | 2023-11-24 | 2023-11-24 | High-power purple crust second laser |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202311581780.9A CN117578175A (en) | 2023-11-24 | 2023-11-24 | High-power purple crust second laser |
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