CN119231302A - High-power mid-infrared fiber gas laser based on spectral beam combining - Google Patents
High-power mid-infrared fiber gas laser based on spectral beam combining Download PDFInfo
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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
- H01S3/14—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range characterised by the material used as the active medium
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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
- H01S3/005—Optical devices external to the laser cavity, specially adapted for lasers, e.g. for homogenisation of the beam or for manipulating laser pulses, e.g. pulse shaping
- H01S3/0071—Beam steering, e.g. whereby a mirror outside the cavity is present to change the beam direction
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Abstract
A high-power mid-infrared optical fiber gas laser based on spectrum beam combination comprises an acetylene fiber gas laser, a dichroic mirror, a reflecting mirror group and a diffraction grating, wherein the acetylene fiber gas laser is used as a laser light source for grating beam combination, laser spectrums output by each path of the acetylene fiber gas laser contain two different wavelengths, the dichroic mirror is respectively arranged on an output light path of each path of the acetylene fiber gas laser and used for separating lasers with two wavelength components in the output lasers of the corresponding acetylene fiber gas laser, the five paths of the acetylene fiber gas lasers are respectively subjected to light splitting through the corresponding dichroic mirror to obtain ten paths of lasers with different wavelengths, the ten paths of lasers are respectively subjected to light path adjustment through the corresponding reflecting mirror group and then are incident to the diffraction grating at different angles, the ten paths of incident lasers are diffracted in the same direction of the diffraction grating, and have the same diffraction angle, so that spectrum beam combination is realized, and the upper limit of the existing power is broken through.
Description
Technical Field
The invention mainly relates to the technical field of optical fiber gas lasers, in particular to a high-power mid-infrared optical fiber gas laser based on spectrum beam combination.
Background
3. The infrared laser in the μm wave band has important application value in the fields of biomedical science, environmental monitoring, material processing and the like, and the implementation means mainly comprise a gas laser, a solid laser, an optical fiber laser, a quantum cascade laser and the like. The fiber laser has the characteristics of compact structure, convenient thermal management, high conversion efficiency, good beam quality and the like, and is an important way for realizing high-efficiency compact high-power middle infrared laser output. However, the soft glass fiber used by the traditional mid-infrared fiber laser has the problems of poor chemical stability, low damage threshold and the like, and restricts the improvement of laser power. The appearance of the hollow fiber provides a new way for realizing the mid-infrared laser, the gas is filled into the hollow fiber, the laser output is realized by utilizing the interaction of the light and the gas, and the novel laser-fiber gas laser is developed.
Currently, the optical fiber gas lasers generating the wave band mainly comprise a single-pass structure optical fiber gas laser, a resonant cavity structure optical fiber gas laser and an amplifier structure optical fiber gas laser. Fiber gas lasers of single pass construction are often difficult to achieve high power output because the laser passes through the fiber only once, there is no opportunity for multiple round trip amplification, and the hollow fiber coupling end face is vulnerable to damage under high power pumping. Although the resonant cavity structure optical fiber gas laser can ensure that laser can make round trip in the cavity for many times and effectively amplify, the resonant cavity structure needs to be accurately designed, the alignment precision requirement is high, additional cavity mirrors, supporting structures and the like are needed, the design complexity is increased, meanwhile, the resonant cavity structure needs to be maintained and adjusted more frequently, and the cost is increased. The method is also limited by the fact that the coupling end face of the hollow fiber is easy to damage under high-power pumping, and the output power of the resonant cavity structure fiber gas laser in the 3 mu m wave band is very limited. The amplifier architecture fiber gas lasers typically require high power pump light sources to achieve efficient optical amplification, and developing high power, narrow linewidth, high beam quality pump sources is inherently difficult, and the amplifier architecture requires a complex feedback control system to maintain stable laser output, which increases system complexity and potential failure points.
Disclosure of Invention
Aiming at the technical problems in the prior art, the invention provides a high-power mid-infrared optical fiber gas laser based on spectrum beam combination.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
In one aspect, the invention provides a high-power mid-infrared optical fiber gas laser based on spectrum beam combination, which comprises an acetylene optical fiber gas laser, a dichroic mirror, a reflecting mirror group and a diffraction grating;
five paths of acetylene fiber gas lasers are used as laser sources for grating beam combination, and the laser spectrums output by the acetylene fiber gas lasers in all paths contain two different wavelengths;
The output light paths of the acetylene fiber gas lasers are respectively provided with a dichroic mirror, and the dichroic mirrors are used for separating lasers corresponding to two wavelength components in the output lasers of the acetylene fiber gas lasers;
after five paths of acetylene fiber gas lasers pass through corresponding bicolor mirrors respectively, ten paths of lasers with different wavelengths are obtained;
Ten paths of lasers with different wavelengths respectively pass through the corresponding reflector groups to adjust the light paths, so that the ten paths of lasers with different wavelengths are incident to the diffraction grating at different angles;
Ten paths of incident lasers with different incident angles and different wavelengths are diffracted in the same direction by the diffraction grating, and have the same diffraction angle, so that spectrum beam combination is completed.
Further, the diffraction grating of the present invention is a reflective diffraction grating.
The invention further discloses an acetylene fiber gas laser, which comprises an optical fiber laser, a focusing lens, a gas cavity group, an air core optical fiber and acetylene gas sealed in the gas cavity, wherein the gas cavity group comprises two gas cavities, namely an input end gas cavity and an output end gas cavity, two ends of the air core optical fiber are respectively arranged in the input end gas cavity and the output end gas cavity, the acetylene gas enters the air core optical fiber through the gas cavity group, the optical fiber laser is used for outputting pump light with the wave band of 1.5 mu m, after the pump light with the wave band of 1.5 mu m enters the air core optical fiber through the focusing lens, the acetylene gas absorbs the pump light energy to generate particle number inversion, and then laser output with the wave band of 3.1 mu m is generated through energy level transition, and the laser spectrum of the output laser contains two wavelength components.
Further, the five-path acetylene fiber gas laser in the invention is a first path of acetylene fiber gas laser, a second path of acetylene fiber gas laser, a third path of acetylene fiber gas laser, a fourth path of acetylene fiber gas laser and a fifth path of acetylene fiber gas laser respectively, the pumping sources of the five paths of acetylene fiber gas lasers are fiber lasers with different output wavelengths, and the five pumping source wavelengths of the five paths of acetylene fiber gas lasers respectively correspond to five absorption lines of acetylene gas.
Further, in the invention, the laser spectrum output by the first path of acetylene fiber gas laser contains 3177.488 nm and 3110.420 nm wavelengths, the laser spectrum output by the second path of acetylene fiber gas laser contains 3172.444 nm and 3114.640 nm wavelengths, the laser spectrum output by the third path of acetylene fiber gas laser contains 3167.464 nm and 3118.918nm wavelengths, the laser spectrum output by the fourth path of acetylene fiber gas laser contains 3162.547 nm and 3123.255 nm wavelengths, and the laser spectrum output by the fifth path of acetylene fiber gas laser contains 3157.694 nm and 3127.651 nm wavelengths.
Further, in the invention, the pump source wavelengths of the first path of acetylene fiber gas laser, the second path of acetylene fiber gas laser, the third path of acetylene fiber gas laser, the fourth path of acetylene fiber gas laser and the fifth path of acetylene fiber gas laser are 1534.099nm, 1532.830 nm, 1531.588 nm, 1530.371 nm and 1529.180 nm respectively, which correspond to five absorption lines P (15), P (13), P (11), P (9) and P (7) of acetylene gas respectively.
Further, in the invention, ten paths of incident lasers with different incident angles and different wavelengths are diffracted in the same direction by the diffraction grating, and ten paths of incident lasers have the same diffraction angleAnd the incident angles of the incident lasers with different wavelengths of each path need to satisfy the grating equation:
;
where m is the diffraction order, d is the grating constant, Is the incident angle of the nth path of incident laser light,Is the angle of diffraction which,Represents the wavelength of the n-th incident laser light, n=1, 2,3,..;
according to the grating equation, the incidence angles of ten paths of incident laser are adjusted, so that ten paths of incident laser with different wavelengths are diffracted in the same direction by the diffraction grating.
The longer the wavelength, the larger the corresponding incident angle in the ten paths of incident laser light.
Spectral combining is an important way to achieve high power output. The invention utilizes the grating device to combine the multi-path middle infrared fiber gas lasers with stable performance, finally obtains high-power laser output, and ensures the stability of the performance. Compared with the prior art, the invention has the technical effects that:
1. According to the invention, acetylene gas is used as a gain medium, hollow optical fibers are used as a place where light and substances interact, and laser output of a 3 mu m wave band is realized through acetylene gas particle number inversion.
2. The invention adopts the reflection diffraction grating as a beam combining device to perform spectrum beam combination on the acetylene fiber gas laser with the wave band of 3 mu m to obtain high-power laser output with the wave band of 3 mu m.
3. The invention combines five paths of acetylene fiber gas lasers, each path of laser system works in a stable state, and the risk of hollow fiber damage is avoided while high-power 3 mu m wave band output is obtained.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to the structures shown in these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a high-power mid-IR fiber gas laser based on spectral beam combining in an embodiment;
FIG. 2 is a schematic diagram of a high-power mid-IR fiber gas laser based on spectral beam combining in another embodiment;
FIG. 3 is a schematic representation of energy level transitions of an acetylene (C 2H2) molecular absorption line pump;
FIG. 4 is a schematic diagram of the grating beam combining principle;
FIG. 5 is a schematic diagram of the absorption spectrum of acetylene gas;
FIG. 6 is a schematic diagram of the output spectrum of an acetylene fiber gas laser at a certain absorption line measured by an experiment;
Reference numerals in the drawings:
A. A first path of acetylene fiber gas laser; 1, pumping source of acetylene fiber gas laser in the first path; 6, a first path of hollow optical fiber, f 1, a first path of focusing lens, g 1, a first path of gas cavity group, f 6 and a first path of collimating lens;
B. A second path of acetylene fiber gas laser; 2, a second path of acetylene fiber gas laser pumping source, 7, a second path of hollow fiber, f 2, a second path of focusing lens, g 2, a second path of gas cavity group, f 7, a second path of collimating lens;
C. A third path of acetylene fiber gas laser; the pumping source of the third path of acetylene fiber gas laser, the 8 third path of hollow fiber, the f 3 third path of focusing lens, the g 3 third path of gas cavity group, the f 8 third path of collimating lens;
D. fourth path acetylene fiber gas laser, 4, fourth path acetylene fiber gas laser pumping source, 9, fourth path hollow fiber, f 4, fourth path focusing lens, g 4, fourth path gas cavity group, f 9, fourth path collimating lens;
E. A fifth path of acetylene fiber gas laser, a fifth path of acetylene fiber gas laser pumping source, a 10 path of hollow fiber, a fifth path of focusing lens, a g 5 path of gas cavity group, a f 10 path of collimating lens;
M1, a first dichroic mirror, M2, a second dichroic mirror, M3, a third dichroic mirror, M4, a fourth dichroic mirror, M5, a fifth dichroic mirror, M6, a first reflecting mirror, M7, a second reflecting mirror, M8, a third reflecting mirror, M9, a fourth reflecting mirror, M10, a fifth reflecting mirror, M11, a sixth reflecting mirror, M12, a seventh reflecting mirror, M13, an eighth reflecting mirror, M14, a ninth reflecting mirror, M15, a tenth reflecting mirror, M16, an eleventh reflecting mirror, M17, a twelfth reflecting mirror, M18, a thirteenth reflecting mirror, M19, a fourteenth reflecting mirror, M20 being a fifteenth reflecting mirror, M21, a sixteenth reflecting mirror, M22, a seventeenth reflecting mirror, M23, an eighteenth reflecting mirror, M24, a nineteenth reflecting mirror, M25, a twentieth reflecting mirror, M26, a twenty first reflecting mirror, M27, a twenty second reflecting mirror, M28, a twenty-eighth reflecting mirror, M29, a twenty-fourth reflecting mirror, M29, a twenty-fifth reflecting mirror;
11. Reflection type diffraction grating.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the invention. 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.
Referring to fig. 1, in an embodiment of the present invention, a high-power mid-infrared optical fiber gas laser based on spectrum beam combination is provided, which includes an acetylene fiber gas laser, a dichroic mirror, a mirror group and a diffraction grating, wherein the acetylene fiber gas laser has five paths as laser sources for grating beam combination, the dichroic mirror is used for separating laser light containing two wavelength components output by each path of the acetylene fiber gas laser, the mirror is used for adjusting the optical path, the mirror is used for making laser light with different wavelengths incident on the diffraction grating, and the diffraction grating diffracts the incident light with different wavelengths for spectrum beam combination.
Five paths of acetylene fiber gas lasers are used as laser sources for grating beam combination, and the laser spectrums output by the acetylene fiber gas lasers in all paths contain two different wavelengths. The five-path acetylene fiber gas lasers are respectively a first path of acetylene fiber gas laser A, a second path of acetylene fiber gas laser B, a third path of acetylene fiber gas laser C, a fourth path of acetylene fiber gas laser D and a fifth path of acetylene fiber gas laser E, the pumping sources of the five paths of acetylene fiber gas lasers are fiber lasers with different output wavelengths, and the five pumping source wavelengths of the five paths of acetylene fiber gas lasers respectively correspond to five absorption lines of acetylene gas. The laser spectrum output by the first path of acetylene fiber gas laser A contains、Two different wavelengths. The laser spectrum output by the second path acetylene fiber gas laser B contains、Two different wavelengths. The laser spectrum output by the third path acetylene fiber gas laser C contains、Two different wavelengths. The fourth path of the laser spectrum output by the acetylene fiber gas laser D contains、Two different wavelengths. The laser spectrum output by the fifth path acetylene fiber gas laser E contains、Two different wavelengths.
The output light paths of the acetylene fiber gas lasers are respectively provided with a dichroic mirror, and the dichroic mirrors are used for separating lasers corresponding to two wavelength components in the output lasers of the acetylene fiber gas lasers. A first dichroic mirror M1 is arranged on the output light path of the first path acetylene fiber gas laser A, and the first dichroic mirror M1 is opposite to the first path acetylene fiber gas laser AHas high transmittance toHas high reflectivity. A second dichroic mirror M2 is arranged on the output light path of the second path acetylene fiber gas laser B, and the second dichroic mirror M2 is opposite to the first dichroic mirrorHas high transmittance toHas high reflectivity. A third dichroic mirror M3 is arranged on the output light path of the third path acetylene fiber gas laser C, and the third dichroic mirror M3 is opposite to the first dichroic mirrorHas high transmittance toHas high reflectivity. A fourth dichroic mirror M4 is arranged on the output light path of the fourth path acetylene fiber gas laser D, and the fourth dichroic mirror M4 is opposite toHas high transmittance toHas high reflectivity. A fifth dichroic mirror M5 is arranged on the output light path of the fifth path acetylene fiber gas laser E, and the fifth dichroic mirror M5 is opposite toHas high transmittance toHas high reflectivity.
After five paths of acetylene fiber gas lasers pass through corresponding bicolor mirrors respectively, ten paths of lasers with different wavelengths are obtained, and the wavelengths are 10~Indicating that each wavelength is located in the 3 μm band.
Referring to fig. 1, the total of 25 mirrors reflect 10 laser beams of different wavelengths output from the five-path acetylene fiber gas laser, and the beam path is adjusted so that the beam is incident on the diffraction grating at a specific angle. The diffraction grating is a reflection type grating and is used for combining incident light beams with different incident angles and different wavelengths.
Mirrors M6 to M10 respectively to~Has high reflectivity. The reflectors M11 to M15 are respectively aligned with~Has high reflectivity. The reflectors M16 to M20 are respectively aligned with~Has high reflectivity. The reflectors M21 to M25 are respectively aligned with~Has high reflectivity. The reflectors M26 to M30 are respectively aligned with~Has high reflectivity.
The fifth reflecting mirror M10, the sixth reflecting mirror M11 and the twenty-fifth reflecting mirror M30 are sequentially arranged on the reflecting light path of the first dichroic mirror M1, and the fifth reflecting mirror M10, the sixth reflecting mirror M11 and the twenty-fifth reflecting mirror M30 have the wavelength ofHas a high reflectivity.
The transmission light path of the first dichroic mirror M1 is provided with a fifteenth reflecting mirror M20 and a sixteenth reflecting mirror M21 in sequence, and the fifteenth reflecting mirror M20 and the sixteenth reflecting mirror M21 have the same wavelengthHas a high reflectivity.
The reflection light path of the second dichroic mirror M2 is sequentially provided with a fourth reflecting mirror M9, a seventh reflecting mirror M12 and a twenty-fourth reflecting mirror M29, and the pairs of the fourth reflecting mirror M9, the seventh reflecting mirror M12 and the twenty-fourth reflecting mirror M29 have the wavelength ofHas a high reflectivity.
The transmission light path of the second dichroic mirror M2 is provided with a fourteenth reflecting mirror M19 and a seventeenth reflecting mirror M22 in sequence, and the pairs of the fourteenth reflecting mirror M19 and the seventeenth reflecting mirror M22 have the wavelength ofHas a high reflectivity.
The reflection light path of the third dichroic mirror M3 is sequentially provided with a third reflecting mirror M8, an eighth reflecting mirror M13 and a twenty-third reflecting mirror M28, and the wavelength of the third reflecting mirror M8, the eighth reflecting mirror M13 and the twenty-third reflecting mirror M28 is equal to that of the wavelength of the light beamHas a high reflectivity.
The transmission light path of the third dichroic mirror M3 is sequentially provided with a thirteenth reflecting mirror M18 and an eighteenth reflecting mirror M23, and the thirteenth reflecting mirror M18 and the eighteenth reflecting mirror M23 have the wavelength ofHas a high reflectivity.
The reflection light path of the fourth dichroic mirror M4 is provided with a second reflecting mirror M7, a ninth reflecting mirror M14 and a twenty-second reflecting mirror M27 in sequence, and the pairs of wavelengths of the second reflecting mirror M7, the ninth reflecting mirror M14 and the twenty-second reflecting mirror M27 are as followsHas a high reflectivity.
A twelfth reflecting mirror M17 and a nineteenth reflecting mirror M24 are sequentially arranged on the transmission light path of the fourth dichroic mirror M4, and the twelfth reflecting mirror M17 and the nineteenth reflecting mirror M24 have the wavelength ofHas a high reflectivity.
The reflection light path of the fifth dichroic mirror M5 is provided with a first reflecting mirror M6, a tenth reflecting mirror M15 and a twenty-first reflecting mirror M26 in sequence, and the pair of wavelengths of the first reflecting mirror M6, the tenth reflecting mirror M15 and the twenty-first reflecting mirror M26 areHas a high reflectivity.
The transmission light path of the fifth dichroic mirror M5 is provided with an eleventh reflecting mirror M16 and a twentieth reflecting mirror M25 in sequence, and the pair of the eleventh reflecting mirror M16 and the twentieth reflecting mirror M25 has a wavelength ofHas a high reflectivity.
Ten paths of laser beams with different wavelengths are respectively subjected to light path adjustment through corresponding reflector groups, so that the ten paths of laser beams with different wavelengths are incident to the reflective diffraction grating 11 at different angles.
Ten paths of incident laser beams with different incident angles and different wavelengths are diffracted in the same direction by the reflection type diffraction grating 11, and have the same diffraction angle, so that spectrum beam combination is completed.
In an embodiment, referring to fig. 2, a high-power mid-infrared optical fiber gas laser based on spectrum beam combination is provided, which comprises an acetylene optical fiber gas laser, a dichroic mirror, a reflecting mirror group and a diffraction grating, wherein the acetylene optical fiber gas laser is used as a laser light source for grating beam combination, the dichroic mirror is used for separating laser which is output by each path of the acetylene optical fiber gas laser and contains two wavelength components, the reflecting mirror is used for adjusting a light path and is used for making laser with different wavelengths incident to the diffraction grating, and the diffraction grating diffracts incident light with different wavelengths and is used for spectrum beam combination. The structure of each path of acetylene fiber gas laser is the same, the acetylene fiber gas laser comprises a fiber laser, a focusing lens, a gas cavity group, an air core fiber and acetylene gas sealed in the gas cavity, the gas cavity group comprises two gas cavities, namely an input end gas cavity and an output end gas cavity, two ends of the air core fiber are respectively arranged in the input end gas cavity and the output end gas cavity, the acetylene gas enters the air core fiber through the gas cavity group, the fiber laser is used for outputting pump light with the wave band of 1.5 mu m, after the pump light with the wave band of 1.5 mu m enters the air core fiber through the focusing lens, the acetylene gas absorbs the pump light energy to generate particle number inversion, and then laser output with the wave band of 3.1 mu m is generated through energy level transition, and the laser spectrum of the output laser contains two wavelength components.
Specifically, the first path of acetylene fiber gas laser A comprises a first path of acetylene fiber gas laser pumping source 1, a first path of hollow fiber 6, a first path of focusing lens f 1, a first path of gas cavity group g 1 and a first path of collimating lens f 6;
The second path of acetylene fiber gas laser B comprises a second path of acetylene fiber gas laser pumping source 2, a second path of hollow fiber 7, a second path of focusing lens f 2, a second path of gas cavity group g 2 and a second path of collimating lens f 7;
The third path of acetylene fiber gas laser C, the third path of acetylene fiber gas laser pumping source 3, the third path of hollow fiber 8, the third path of focusing lens f 3, the third path of gas cavity group g 3, the third path of collimating lens f 8;
A fourth path of acetylene fiber gas laser D, a fourth path of acetylene fiber gas laser pumping source 4, a fourth path of hollow fiber 9, a fourth path of focusing lens f 4, a fourth path of gas cavity group g 4 and a fourth path of collimating lens f 9;
A fifth path acetylene fiber gas laser E, a fifth path acetylene fiber gas laser pumping source 5, a fifth path hollow fiber 10, a fifth path focusing lens f 5, a fifth path gas cavity group g 5 and a fifth path collimating lens f 10.
The wavelengths of the first path of acetylene fiber gas laser pumping source 1, the second path of acetylene fiber gas laser pumping source 2, the third path of acetylene fiber gas laser pumping source 3, the fourth path of acetylene fiber gas laser pumping source 4 and the fifth path of acetylene fiber gas laser pumping source 5 are 1534.099 nm, 1532.830 nm, 1531.588 nm, 1530.371 nm and 1529.18nm respectively, and correspond to five absorption lines P (15), P (13), P (11), P (9) and P (7) of acetylene gas respectively, as shown in fig. 5. Reference is made to table 1 for a comparison of absorption lines and emission lines of acetylene fiber gas laser pumps.
TABLE 1
The first path of acetylene fiber gas laser pump source 1, the second path of acetylene fiber gas laser pump source 2, the third path of acetylene fiber gas laser pump source 3, the fourth path of acetylene fiber gas laser pump source 4 and the fifth path of acetylene fiber gas laser pump source 5 are used as pump sources of the acetylene fiber gas laser. The lens f 1~ f5 is a focusing lens used for focusing the light beam output by the optical fiber laser with the wave band of 1.5 μm into the hollow optical fiber, and the lens f 6~ f10 is a collimating lens used for collimating the laser output by the acetylene fiber gas laser. Further, g 1~g5 is five sets of gas chambers for sealing acetylene gas. Each hollow fiber serves as a site where the 1.5 μm pump light and acetylene gas interact with substances.
When 1.5 mu m pump light is coupled into the hollow fiber, the intermediate infrared laser output of 3.1 mu m wave band is generated, and because the wavelengths of the five paths of 1.5 mu m pump sources are different, the output wavelengths of the five paths of acetylene fiber gas lasers are also different, and each path of acetylene fiber gas lasers contains two different wavelength components.
FIG. 3 is a schematic representation of energy level transitions of an acetylene (C 2H2) molecular absorption line pump. When acetylene molecules are pumped by the P (i) absorption line, they are pumped fromOn the vibration ground stateIs shifted to the upper energy levelOn vibration dynamicsIs a dynamic state of rotation. According to the Boltzmann distribution, at normal temperature exceptThe number of particles on other vibration states is almost 0, and the upper energy levelVibration dynamics and lower energy levelThe vibrational state forms a population inversion. According to the law of transition selection(Corresponding to the R branch,Corresponding to P branches, whereinRefers to the difference between the upper and lower rotational energy levels), the upper energy level of excitationVibration-dynamic particle transition toOn vibration dynamicsAndRespectively emit outAndTwo laser transition lines, where i-2 and i represent the number of rotational quanta at the energy level under transition.
Figure 4 is a schematic diagram of the grating beam combining principle,、AndRepresenting the angle of incidence (the angle between the incident light and the normal to the plane of the grating),The diffraction angle (the angle between the diffracted light and the normal to the plane of the grating) is indicated. Incident light with different directions and different wavelengths is incident to the grating and is emitted along the same direction after being diffracted by the grating, and the process needs to satisfy a grating equation:
;
where m is the diffraction order, d is the grating constant, (Corresponding to FIG. 4)、Or (b)) Is the angle of incidence and,(Corresponding to FIG. 4)) Is the angle of diffraction which,Representing wavelength.
For the invention, ten paths of incident lasers with different incident angles and different wavelengths are diffracted in the same direction by the diffraction grating, and ten paths of incident lasers have the same diffraction angleAnd the incident angles of the incident lasers with different wavelengths of each path need to satisfy the grating equation:
;
where m is the diffraction order, d is the grating constant, Is the incident angle of the nth path of incident laser light,Is the angle of diffraction which,Represents the wavelength of the n-th incident laser light, n=1, 2,3,..;
According to the grating equation, the incidence angles of ten paths of incident laser are adjusted, so that ten paths of incident laser with different wavelengths are diffracted in the same direction by the diffraction grating and are emitted along the same direction, namely the diffraction angles are the same. The longer the wavelength, the larger the corresponding incident angle in the ten paths of incident laser light. Therefore, the lasers with different wavelengths are incident according to a certain angle, so that the spectrum combination can be realized.
FIG. 5 is a schematic diagram of the absorption spectrum of acetylene gas. The acetylene gas contains a plurality of absorption lines, wherein the wavelength is shorter as R absorption lines, and the wavelength is longer as P absorption lines.
Fig. 6 is a schematic diagram of an output spectrum of an acetylene fiber gas laser under a certain absorption line, wherein the output laser is in a 3 μm band, and the laser spectrum contains two different wavelength components.
The output wavelength of the pumping source 1 of the first path of acetylene fiber gas laser is 1534.099nm, after the laser is focused and coupled into a hollow fiber in a gas cavity, the generated laser contains 3177.488 nm and 3110.420 nm wavelengths which are respectively usedAndAnd (3) representing. A first dichroic mirror M1 having a wavelength ofHas high transmittance to the laser light of wavelength ofThe second path of acetylene fiber gas laser pump source 2 has output wavelength 1532.830 nm, and after being focused and coupled into hollow fiber in the gas cavity, the generated laser contains 3172.444 nm and 3114.640 nm wavelengths, which are respectively usedAndAnd (3) representing. The second dichroic mirror M2 has a wavelength ofHas high transmittance to the laser light of wavelength ofHas a high reflectivity. The third path of pumping source 3 of acetylene fiber gas laser has output wavelength 1531.588 nm, and after being coupled into hollow fiber in the gas cavity, the generated laser contains 3167.464 nm and 3118.918 nm wavelengths, which are respectively usedAndAnd (3) representing. The third dichroic mirror M3 has a wavelength ofHas high transmittance to the laser light of wavelength ofThe fourth path of acetylene fiber gas laser pumping source 4 has output wavelength of 1530.371 nm, and after being focused and coupled into hollow fiber in the gas cavity, the generated laser contains 3162.547 nm and 3123.255 nm wavelengths, which are respectively usedAndAnd (3) representing. A fourth dichroic mirror M4 having a wavelength ofHas high transmittance to the laser light of wavelength ofThe fifth path of acetylene fiber gas laser pump source 5 has output wavelength 1529.18 nm, and after being focused and coupled into the hollow fiber in the gas cavity, the generated laser contains 3157.694 nm and 3127.651 nm wavelengths, which are respectively usedAndAnd (3) representing. The fifth dichroic mirror M5 has a wavelength ofHas high transmittance to the laser light of wavelength ofHas a high reflectivity.
Mirrors M6 to M10 respectively to~Has high reflectivity. The reflectors M11 to M15 are respectively aligned with~Has high reflectivity. The reflectors M16 to M20 are respectively aligned with~Has high reflectivity. The reflectors M21 to M25 are respectively aligned with~Has high reflectivity. The reflectors M26 to M30 are respectively aligned with~Has high reflectivity.
The laser emitted by the five-path acetylene fiber gas laser is split by the dichroic mirrors M1-M5 to form two parts, one part of the laser is continuously transmitted along the original light path due to the high transmittance of the dichroic mirrors, and the other part of the laser is continuously transmitted after the light path is deflected due to the high reflectivity of the dichroic mirrors. The reflectors M6-M20 are 45 DEG reflectors for deflecting the light path to guide the light beam to propagate. Mirrors M21 to M25 are made to reflect by adjusting angles~The laser light is incident on the reflection type diffraction grating 11 at a specific angle. The mirrors M26 to M30 reflect the light by adjusting the angle~The laser light is incident on the grating at a specific angle.~The wavelength is decreased, the angle of incidence on the reflective diffraction grating 11 is decreased, and according to the grating equation, ten light beams are diffracted along the same direction and have the same diffraction angle as long as the incidence angle is properly adjusted, so that spectrum beam combination is realized.
The invention breaks through the upper power limit of the acetylene fiber gas laser with the wave band of 3 mu m based on spectrum beam combination. Each path of acetylene fiber gas laser works in a stable state, the output power of each path of acetylene fiber gas laser is in a safe state, the damage of the coupling end face of the hollow fiber is avoided, and high-power 3 mu m-band laser output with good stability can be realized after beam combination. In other non-spectral beam combining solutions, the output of the fiber gas laser becomes unstable under high power pumping, and a complex feedback control system is required to maintain stable laser output, which increases the complexity of the system and potential failure points, so that the present invention does not have the advantages of the present invention.
The invention uses the diffraction grating to combine the laser output by the mid-infrared fiber gas laser, thereby breaking through the existing upper power limit. In other non-spectrum beam combination technical schemes, in order to obtain the same effect, the pumping power needs to be greatly improved, and the hollow fiber coupling end face is damaged under high-power pumping, so that the improvement of the output power is restricted.
The invention is not a matter of the known technology.
The technical features of the above embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples merely represent a few embodiments of the present application, which are described in more detail and are not to be construed as limiting the scope of the application. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the application, which are all within the scope of the application. Accordingly, the scope of the application should be assessed as that of the appended claims.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (7)
1. The high-power mid-infrared optical fiber gas laser based on spectrum beam combination is characterized by comprising an acetylene optical fiber gas laser, a dichroic mirror, a reflecting mirror group and a diffraction grating;
The laser spectrum output by each path of acetylene fiber gas laser comprises two different wavelengths, wherein the five paths of acetylene fiber gas lasers are respectively a first path of acetylene fiber gas laser, a second path of acetylene fiber gas laser, a third path of acetylene fiber gas laser, a fourth path of acetylene fiber gas laser and a fifth path of acetylene fiber gas laser, pumping sources of the five paths of acetylene fiber gas lasers are fiber lasers with different output wavelengths, and the five pumping source wavelengths of the five paths of acetylene fiber gas lasers respectively correspond to five absorption lines of acetylene gas;
The output light paths of the acetylene fiber gas lasers are respectively provided with a dichroic mirror, and the dichroic mirrors are used for separating lasers corresponding to two wavelength components in the output lasers of the acetylene fiber gas lasers;
after five paths of acetylene fiber gas lasers pass through corresponding bicolor mirrors respectively, ten paths of lasers with different wavelengths are obtained;
Ten paths of lasers with different wavelengths respectively pass through the corresponding reflector groups to adjust the light paths, so that the ten paths of lasers with different wavelengths are incident to the diffraction grating at different angles;
Ten paths of incident lasers with different incident angles and different wavelengths are diffracted in the same direction by the diffraction grating, and have the same diffraction angle, so that spectrum beam combination is completed.
2. The spectrally combined high power mid-infrared fiber gas laser of claim 1, wherein the diffraction grating is a reflective diffraction grating.
3. The high-power mid-infrared optical fiber gas laser based on spectrum beam combination according to claim 2, wherein the acetylene optical fiber gas laser comprises an optical fiber laser, a focusing lens, a gas cavity group, an air core optical fiber and acetylene gas sealed in the gas cavity, the gas cavity group comprises two gas cavities, namely an input end gas cavity and an output end gas cavity, two ends of the air core optical fiber are respectively arranged in the input end gas cavity and the output end gas cavity, the acetylene gas enters the air core optical fiber through the gas cavity group, the optical fiber laser is used for outputting pump light with a wavelength band of 1.5 μm, after the pump light with the wavelength band of 1.5 μm enters the air core optical fiber through the focusing lens, the acetylene gas absorbs the pump light energy to generate particle number inversion, and then laser output with the wavelength band of 3.1 μm is generated through energy level transition, and the laser spectrum of the output laser comprises two wavelength components.
4. The high-power mid-infrared optical fiber gas laser based on spectrum combination according to claim 3, wherein the laser spectrum output by the first path of acetylene optical fiber gas laser contains 3177.488 nm and 3110.420 nm wavelengths, the laser spectrum output by the second path of acetylene optical fiber gas laser contains 3172.444 nm and 3114.640 nm wavelengths, the laser spectrum output by the third path of acetylene optical fiber gas laser contains 3167.464 nm and 3118.918nm wavelengths, the laser spectrum output by the fourth path of acetylene optical fiber gas laser contains 3162.547 nm and 3123.255 nm wavelengths, and the laser spectrum output by the fifth path of acetylene optical fiber gas laser contains 3157.694 nm and 3127.651 nm wavelengths.
5. The high-power mid-infrared optical fiber gas laser based on spectrum combination according to claim 3, wherein the pump source wavelengths of the first path of acetylene fiber gas laser, the second path of acetylene fiber gas laser, the third path of acetylene fiber gas laser, the fourth path of acetylene fiber gas laser and the fifth path of acetylene fiber gas laser are 1534.099 nm, 1532.830 nm, 1531.588 nm, 1530.371 nm and 1529.180 nm respectively, which correspond to five absorption lines P (15), P (13), P (11), P (9) and P (7) of acetylene gas respectively.
6. The high power mid-infrared fiber gas laser based on spectral beam combining according to any one of claims 1-5, wherein ten incident lasers of different angles of incidence and different wavelengths are diffracted in the same direction by the diffraction grating, the ten incident lasers having the same diffraction angleAnd the incident angles of the incident lasers with different wavelengths of each path need to satisfy the grating equation:
;
where m is the diffraction order, d is the grating constant, Is the incident angle of the nth path of incident laser light,Is the angle of diffraction which,Represents the wavelength of the n-th incident laser light, n=1, 2,3,..;
according to the grating equation, the incidence angles of ten paths of incident laser are adjusted, so that ten paths of incident laser with different wavelengths are diffracted in the same direction by the diffraction grating.
7. The high power mid-infrared fiber gas laser based on spectral combining of claim 6, wherein the longer the wavelength, the larger the corresponding angle of incidence of ten incident lasers.
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| CN104901149A (en) * | 2015-05-05 | 2015-09-09 | 中国科学院上海光学精密机械研究所 | Spectral beam combining system based on three diffraction gratings |
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| CN104901149A (en) * | 2015-05-05 | 2015-09-09 | 中国科学院上海光学精密机械研究所 | Spectral beam combining system based on three diffraction gratings |
| CN115513764A (en) * | 2022-09-15 | 2022-12-23 | 香港理工大学深圳研究院 | All-optical Q-switch, all-optical Q-switch laser and pulse laser output method thereof |
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