CN114865437A - 2-micron and 3-micron dual-wavelength solid intermediate infrared laser - Google Patents
2-micron and 3-micron dual-wavelength solid intermediate infrared laser Download PDFInfo
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- 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
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- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/09—Processes or apparatus for excitation, e.g. pumping
- H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
- H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
- H01S3/094042—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light of a fibre laser
- H01S3/094046—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light of a fibre laser of a Raman fibre laser
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- H—ELECTRICITY
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- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/09—Processes or apparatus for excitation, e.g. pumping
- H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
- H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
- H01S3/0941—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light of a laser diode
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- H—ELECTRICITY
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- 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
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- H01S3/1603—Solid materials characterised by an active (lasing) ion rare earth
- H01S3/161—Solid materials characterised by an active (lasing) ion rare earth holmium
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Abstract
The invention relates to a 2 mu m and 3 mu m dual-wavelength solid mid-infrared laser, which comprises a pump laser, a collimation focusing system, a resonant cavity and a filter plate which are sequentially arranged along a light path; the resonator cavity includes a laser input mirror A, Ho 3+ An ion-doped laser crystal and a laser output mirror A. According to the invention, 2-micron and 3-micron lasers can be simultaneously output by optimizing parameters such as crystal doping concentration, matrix material selection, crystal length and the like; high power can be realized by optimizing pumping and resonant cavity structure>5W), high skew efficiency (>40%), high beam quality (M) 2 <1.5) and 3 μm laser are simultaneously output, and the requirements of plastic laser welding and laser medical treatment are met.
Description
Technical Field
The invention relates to a 2-micron and 3-micron dual-wavelength solid intermediate infrared laser, and belongs to the technical field of solid intermediate infrared lasers.
Background
The 2-micron and 3-micron mid-infrared lasers have important application values in the fields of material processing, gas detection, medical diagnosis, precision measurement, photoelectric countermeasure and the like. The polymer plastic has extremely strong intrinsic absorption (the absorption rate exceeds 80%) to laser with the wavelength of 2 mu m and 3 mu m, so that the polymer plastic has great application potential in the field of plastic laser welding, does not need to manufacture additives of an absorption layer, ensures the welding quality and reduces the cost, and has been successfully applied to welding of medical plastic appliances, plastic parts of white household appliances and plastic parts of automobiles. 2 μm and 3 μm wave band laser is positioned at the water strong absorption peak, so that the laser plays an important role in cutting and ablating water-rich tissues and assisting quality; the absorption coefficient of water to 3 mu m laser is as high as 10 -4 cm -1 The utility model can be absorbed by relatively shallow water-rich soft tissues, and can realize accurate cutting without generating thermal damage to surrounding areas, thus being an ideal tool for surgical fine surgery; the absorption coefficient of water to 2 mu m laser is relatively low by 10 -1 cm -1 The depth of penetrating the tissue is deeper than that of laser with the laser diameter of 3 mu m, and the laser has important application in the aspects of blood coagulation and hemostasis; at present, 2 μm and 3 μm mid-infrared lasers are used in dental and surgical clinical medicine.
The current technical means for generating 2-micron and 3-micron mid-infrared lasers are mainly divided into two categories: the first is the direct emission of stimulated radiative transition, including ion doped solid or fiber laser, semiconductor laser, etc.; another class of non-linear frequency transform techniques includes raman, supercontinuum, difference frequency, and OPO, among others. Except for holmium (Ho) 3+ ) Ion-doped fiber lasers, other technical means are difficult to realize the simultaneous output of 2-micron and 3-micron mid-infrared lasers. Currently, at Ho 3+ The mid-infrared laser cascade output of 2-micron and 3-micron dual wavelengths has been realized in ion-doped fluoride optical fibers. However, the drawing process of rare earth ion doped sulfide and fluoride optical fiber is immature in China, although research units such as Harbin engineering university and Jilin university have made great progress,but only the company LeVerreFluor, France, and Fiberlabs, Japan, can provide commercial products internationally, which are very expensive, and some of the products are banned domestically; the development of middle infrared optical fiber functional devices such as a beam combiner, a coupler, an isolator, a circulator, a mode locking device and the like is immature, the commercialization level is low, the high-quality fluoride optical fiber processing technology is incomplete, the popularization degree is low, and full fiberization is difficult to realize; chalcogenide and fluoride glass fibers are fragile, low in melting point, easy to damage and strong in nonlinear effect, and the high-power high-energy 2-micron and 3-micron dual-wavelength mid-infrared laser operation is difficult to realize. Thus, although Ho 3+ The ion-doped fluoride optical fiber realizes the cascade output of mid-infrared laser with double wavelengths of 2 mu m and 3 mu m, but the gain material and functional components of the core optical fiber depend on import and are limited by people.
Compared with a mid-infrared optical fiber material, the domestic solid laser crystal growth preparation technology is advanced internationally, the laser crystal damage threshold is high, the nonlinear effect is weak, the cost is low, and an ideal and reliable research platform is provided for further developing high-power high-energy mid-infrared 2-micron and 3-micron dual-wavelength laser technologies. So far, no report exists on the simultaneous output of the infrared laser in the 2 μm and 3 μm dual-wavelength solid.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a 2 mu m and 3 mu m dual-wavelength solid intermediate infrared laser, which adopts a semiconductor laser or an optical fiber laser to pump Ho 3+ The ion-doped laser crystal can realize the simultaneous output of 2-micron and 3-micron lasers by optimizing the parameters of crystal doping concentration, matrix material selection, crystal length and the like; in addition, 2-micrometer and 3-micrometer lasers with high power, high efficiency and high beam quality are simultaneously output by optimizing the pumping and resonant cavity structures, and the requirements of plastic laser welding and laser medical treatment are met.
The technical scheme of the invention is as follows:
a2 μm and 3 μm dual-wavelength solid mid-infrared laser comprises a pump laser, a collimation focusing system, a resonant cavity and a filter A which are arranged along a light path in sequence; the resonator cavity includes a laser input mirror A, Ho 3+ Ion-doped laser crystalA body and a laser output mirror A;
the pump laser is a semiconductor laser or a fiber Raman laser, and the working wavelength of the pump laser is 1120-1150 nm;
the Ho 3+ The ion-doped laser crystal is Ho 3+ Ion-doped fluoride crystals or Ho 3+ Ion-doped sesquioxide crystals;
after the pump light output by the pump laser is collimated by the collimating and focusing system, the pump light enters the resonant cavity, and the pump light enters the Ho after passing through the laser input mirror A 3+ Ion doping laser crystal, for the Ho 3 + Pumping the ion-doped laser crystal, forming optical cascade oscillation in the resonant cavity, generating mid-infrared laser with the wavelength of 2 microns and 3 microns, and coupling and outputting the mid-infrared laser by the laser output mirror A; the filter A filters out the residual pump light and outputs mid-infrared laser with the wavelength of 2 mu m and 3 mu m.
The invention provides a 2 mu m and 3 mu m dual-wavelength solid mid-infrared laser which comprises the following components in percentage by weight: as shown in FIG. 1, the processes participating in the cascade oscillation of 2 μm and 3 μm include Ground State Absorption (GSA), Excited State Absorption (ESA) 1 、ESA 2 )、 5 I 6 → 5 I 7 And 5 I 7 → 5 I 8 stimulated emission transition process and energy up-conversion (ETU) 1 、ETU 2 ) Cross Relaxation (CR) 1 、CR 2 ) And the like non-radiative transition processes. 5 I 7 The energy level is the intermediate energy level of the cascade transition, and the particle number of the energy level is mainly derived from 5 I 6 → 5 I 7 Transition, ESA 1 、ETU 1 And CR 1 、CR 2 And so on.
Under the condition of certain pumping power, when the doping concentration is higher, ETU 1 The process is dominant and will accelerate "emptying" 5 I 7 The energy level particle number is simultaneously superposed with the concentration quenching effect, thereby being more beneficial to realizing 5 I 6 And 5 I 7 particle number inversion between energy levels, but it is difficult to achieve the same 5 I 7 And 5 I 8 the population inversion of the energy levels, so only 3 μm laser emission can be achieved; when the doping concentration is too low, the upper energy level of the 2.9 μm transition laser 5 I 6 The service life is far less than the lower energy level of laser 5 I 7 This makes it difficult to form an effective inversion population maintaining laser oscillation, and there is a so-called "laser self-termination" effect, and only 2 μm laser emission can be realized. Therefore, it is difficult to achieve simultaneous emission of mid-infrared laser light of 2 μm and 3 μm both at too high and too low doping concentrations. Comprehensively considering the radiative transition and non-radiative transition process, the doping concentration and length of the crystal and other parameters, and the one-way gain coefficient G of 2 mu m 2μm And a one-way gain factor G of 3 μm 3μm Respectively shown in formula (I) and formula (II):
G 2μm ＝[τ 2 βσ el2 +(τ 2 +τ 3 β)σ al3 ]P a /(A×hν p )-Nσ al2 L (I)
in the formula (I), tau 2 Is composed of 5 I 7 Fluorescence lifetime of energy level,. sigma el2 Is a stimulated emission cross section of 2 μm, σ al2 Is a stimulated absorption cross-section of 2 μm, beta is 5 I 6 → 5 I 7 Fluorescence branch ratio of transition, h is Planck constant, v p Representing the frequency of the pump light, A denotes the pump light facet, L is the crystal length, P a Representing the absorbed pump power, and N representing the initial particle number of the system;
G 3μm ＝[τ 3 σ el3 -τ 2 β)σ al3 ]P a /(A×hν p ) (II)
in the formula (II), τ 3 Is composed of 5 I 6 Fluorescence lifetime of energy level,. sigma el3 Stimulated emission cross section, σ, of 3 μm al3 A stimulated absorption cross-section of 3 μm;
therefore, by optimizing Ho 3+ Ion doping concentration, crystal matrix material and length, pumping and other parameters to realize the simultaneous emission of 2 micron and 3 micron middle infrared laser.
According to the invention, the Ho is preferable 3+ The doping concentration range of the ion-doped laser crystal is 0.5-1.5 at.%; by pumping the dopingThe laser crystal in the range can realize the cascade simultaneous output of 2-micron and 3-micron mid-infrared lasers.
According to the invention, the Ho is preferable 3+ The ion-doped fluoride crystal is Ho: YLiF 4 (Ho: YLF) crystal, Ho: LuLiF 4 (Ho: LLF) crystal, Ho: BaYF 4 (Ho: BYF) crystal, Ho: CaF 2 And (4) crystals. Wherein, the YLF matrix crystal has low phonon energy and weak thermal effect; the LLF matrix crystal has wide light transmission range (0.3-16 μm) and high damage threshold; the BYF substrate crystal has long fluorescence lifetime and low threshold; CaF 2 The absorption and emission peaks of the host crystal are wide.
Ho 3+ The ion-doped sesquioxide crystal is Ho: Lu 2 O 3 Or Ho: Y 2 O 3 The phonon energy of the sesquioxide crystal is low.
According to the invention, the pump laser is preferably a fiber Raman laser with an output wavelength of 1150 nm. The wavelength is located at 5 I 8 → 5 I 6 The wavelength of the absorption peak is relatively longer, so that the absorption pair of the excited state can be reduced 5 I 7 The loss of energy level particle number, good light beam quality, high conversion efficiency and high output power.
According to the invention, the laser input mirror A is preferably plated with a pumping light antireflection film and high reflection films with the wavelengths of 2 μm and 3 μm; the transmittance of the pump light antireflection film to the pump light is more than 95%, and the reflectivity of the high-reflection film to the wavelengths of 2 mu m and 3 mu m is more than 99.8%;
the laser output mirror A is plated with partial transmission films with the wavelengths of 2 mu m and 3 mu m, the transmittance of the partial transmission films with the wavelengths of 2 mu m is 10-27%, and the transmittance of the partial transmission films with the wavelengths of 3 mu m is 10-38%.
According to the invention, the resonant cavity also comprises a 45-degree harmonic mirror, a laser output mirror B and a filter plate B, wherein the 45-degree harmonic mirror is arranged at the Ho 3+ The 45-degree harmonic mirror forms a 45-degree included angle with the light path between the ion-doped laser crystal and the laser output mirror A; the laser output mirror B and the filter plate B are sequentially arranged on one side of the 45-degree harmonic mirror;
laser input mirror A, Ho 3+ The ion-doped laser crystal and the laser output mirror A form a3 muThe m resonant cavity generates 3 mu m laser, the laser is coupled and output by a laser output mirror A, and the filter A filters residual 1150nm pump light and outputs 3 mu m mid-infrared laser;
laser input mirror A, Ho 3+ The ion-doped laser crystal, the 45-degree harmonic mirror and the laser output mirror B form a 2-micron resonant cavity to generate 2-micron laser, the 2-micron laser is coupled and output by the laser output mirror B, and the filter B filters residual 1150nm pump light and outputs 2-micron-wavelength mid-infrared laser.
The design of the composite cavity can realize the mode matching of the pump light and the oscillation light according to the gain of the 2 mu m laser and the 3 mu m laser and the size of the oscillation light spot in the lossy cavity, and improve the output power and the beam quality of the output 2 mu m laser and the 3 mu m laser.
According to the invention, the laser input mirror A is preferably plated with a pumping light antireflection film and high reflection films with the wavelengths of 2 μm and 3 μm; the transmittance of the pump light antireflection film to pump light is more than 95%, and the reflectivity of the high-reflection film to wavelengths of 2 mu m and 3 mu m is more than 99.8%;
the 45-degree harmonic mirror is plated with a 3-micron antireflection film and a 2-micron high-reflection film, the transmittance of the 45-degree harmonic mirror to the wavelength of 3 microns is more than 99.5%, and the reflectivity of the 45-degree harmonic mirror to the wavelength of 2 microns is more than 99.8%;
the laser output mirror A is plated with partial transmission films with the wavelengths of 2 microns and 3 microns, the transmittance of the partial transmission films with the wavelengths of 2 microns is more than 99.5%, and the transmittance of the partial transmission films with the wavelengths of 3 microns is 20%;
the laser output mirror B is coated with partial transmission films with the wavelengths of 2 mu m and 3 mu m, the transmittance of the partial transmission films with the wavelengths of 2 mu m is 20%, and the transmittance of the partial transmission films with the wavelengths of 3 mu m is more than 99.5%.
According to the invention, the laser input mirror A, the laser output mirror B and the 45-degree harmonic mirror are preferably made of calcium fluoride crystals or ZnSe crystals. The calcium fluoride crystal and the ZnSe crystal have high transmittance to the mid-infrared laser with 2 mu m and 3 mu m, and realize the functions of positive feedback and mode selection of the resonant cavity.
According to the invention, the angle a between the filter A/the filter B and the light path preferably satisfies the following condition: 0 ° < a <10 °.
According to the invention, the filter A/the filter B is preferably a germanium sheet or a harmonic lens with a medium film evaporated.
According to the present invention, preferably, the output mode of the semiconductor laser is one of a free space direct output mode, an optical fiber coupling output mode, a stacked array output mode and a linear array output mode.
The invention has the beneficial effects that:
1. the invention utilizes 1150nm fiber laser to pump Ho 3+ The ion-doped crystal can realize the cascade output of mid-infrared lasers with the wavelength of 2 mu m and 3 mu m simultaneously, and has high efficiency and good beam quality.
2. The invention can output mid-infrared laser with 2 μm and 3 μm simultaneously, can greatly improve the absorption efficiency of transparent or white plastic materials, and has important application in medical diagnosis and surgery.
3. At present, no report is found on a solid laser for realizing the simultaneous output of 2 mu m and 3 mu m mid-infrared lasers, and Ho is optimized 3+ High power can be realized by parameters such as ion doping concentration, crystal matrix, length and the like and a resonant cavity structure>5W), high skew efficiency (>40%), high beam quality (M) 2 <1.5) and 3 μm laser are simultaneously output, and the requirements of plastic laser welding and laser medical treatment are met.
Drawings
FIG. 1 shows Ho 3+ An ion laser crystal energy level schematic;
FIG. 2 is a schematic structural diagram of a 2 μm and 3 μm dual-wavelength solid-state mid-infrared laser provided in example 1 of the present invention;
FIG. 3 is a graph of the output power of 2 μm mid-IR laser obtained in example 1 of the present invention;
FIG. 4 is a3 μm mid-IR laser output power curve obtained in example 1 of the present invention;
FIG. 5 is a graph of 2 μm and 3 μm mid-infrared laser spectra obtained in example 1 of the present invention;
FIG. 6 is a schematic structural diagram of a 2 μm and 3 μm dual-wavelength solid-state mid-infrared laser provided in example 4 of the present invention;
1. pump laser, 2, collimation focusing system, 3, laser input mirror A, 4, Ho 3+ Ion-doped laser crystal, 5, laserOutput mirrors A and 6, filters A, 7 and 45-degree harmonic mirrors, 8, laser output mirrors B and 9 and a filter B.
Detailed Description
The invention is further described below, but not limited thereto, with reference to the following examples and the accompanying drawings.
Example 1
A2 μm and 3 μm dual-wavelength solid mid-infrared laser is shown in FIG. 2, and comprises a pump laser 1, a collimation focusing system 2, a resonant cavity and a filter A6 which are arranged along a light path in sequence; the resonant cavity comprises laser input mirrors A3 and Ho 3+ The ion-doped laser crystal 4 and the laser output mirror A5;
in this example, Ho 3+ The ion-doped laser crystal 4 is Ho, YLF crystal, Ho 3+ The ion doping concentration is 1 at.%, and the temperature of the Ho: YLF crystal placed in the water-cooling heat sink is controlled at<20℃。
The pump laser 1 is a fiber laser with an operating wavelength of 1150 nm.
Pumping light output by the 1150nm optical fiber laser enters a resonant cavity after being collimated by a collimating and focusing system 2, the pumping light enters a Ho: YLF crystal after passing through a laser input mirror, the Ho: YLF crystal is pumped, cascade laser oscillation is formed in the resonant cavity, 2-micrometer and 3-micrometer mid-infrared lasers are generated, and the coupled output is realized through a laser output mirror A5; the filter a6 filters out the residual pump light and outputs 2 μm and 3 μm laser light.
The working principle of the 2 mu m and 3 mu m dual-wavelength solid intermediate infrared laser provided by the invention is as follows: the crystal of Ho and YLF absorbs 1150nm pump light, and the particles are selected from 5 I 8 Transition of energy level to 5 I 6 Energy level, Ho 3+ The ion doping concentration and the pumping intensity are enough to ensure that 5 I 6 And 5 I 7 the energy level generates population inversion, and the oscillation condition that the gain is larger than the loss by 3 mu m is satisfied. At the same time, the user can select the desired position, 5 I 6 → 5 I 7 the energy level transition is 5 I 7 → 5 I 8 The transition corresponds to the main source of 2 μm emission inversion particle number, and satisfies the oscillation condition that 2 μm gain is larger than loss, and the 2 μm transition in turn promotes the lower energy level of 3 μm transition 5 I 7 The population of the laser is evacuated, thereby improving the efficiency and power of the 3 μm laser emission. Thus, 2 μm and 3 μm cascade emission, the two wavelength lasers contribute to efficiency and power improvements in each other.
The laser input mirror A3 and the laser output mirror A5 are calcium fluoride crystals, have higher transmittance to 2-micrometer and 3-micrometer mid-infrared lasers, reduce absorption loss, and simultaneously realize the functions of positive feedback and mode selection of the resonant cavity.
The angle a of the filter segment and the light path is 0 < a < 10.
The laser input mirror A3 and the laser output mirror A5 are coated with dielectric films, the laser input mirror A3 is coated with a 1150nm pump light antireflection film and high reflection films with the wavelength of 2 mu m and 3 mu m, the transmittance of the pump light antireflection film to 1150nm pump light is more than 95%, and the reflectance of the high reflection film to the wavelength of 2 mu m and 3 mu m is more than 99.8%;
the laser output mirror A5 was coated with a 2 μm and 3 μm wavelength partially transmissive film with a 2 μm wavelength transmittance of 10-27% and a3 μm wavelength transmittance of 10-38%.
The 3 μm power of the infrared laser in the cascade of 2 μm and 3 μm is shown in fig. 3, the 2 μm power is shown in fig. 4, when the laser output mirror a5 is coated with a partial transmission film with the wavelength of 2 μm and 3 μm, the effect is best when the transmittance for 2 μm is 15% and the transmittance for 3 μm is 25%, when the power of the pump laser 1 is 5W, the 3 μm output power is 780mW, and the corresponding tilt efficiency η is 16.9%; the 2 μm output power was 150mW, corresponding to an oblique efficiency η of 2.8%.
Under the same conditions, the output power of the 3-micron single-wavelength oscillation is 400mW, and the 3-micron laser output power is improved by 100 percent and the laser threshold is reduced by 15 percent compared with the output power of the 3-micron laser during the single-wavelength oscillation.
As shown in fig. 5, the 2 μm and 3 μm cascade mid-infrared laser output spectra vary with pump power. In the cascade oscillation process, 3 mu m laser oscillates preferentially, and 2 mu m laser starts oscillation along with the increase of pumping power.
Example 2
A 2 μm and 3 μm dual wavelength solid state mid-ir laser is provided according to example 1, with the difference that:
in this example, the pump laser 1 is a semiconductor laser, the operating wavelength is 1120-1150nm, the pump laser 1 is fiber-coupled output, and the angle a between the filter a6 and the optical path satisfies 0 ° < a <10 °.
In this example, Ho 3+ The ion-doped laser crystal 4 is Ho 3+ Ion-doped sesquioxide crystals; ho 3+ The ion-doped sesquioxide crystal is Ho: Lu 2 O 3 Or Ho: Y 2 O 3 Doping concentration 1.5 at.%.
Example 3
A 2 μm and 3 μm dual wavelength solid state mid-ir laser is provided according to example 1, with the difference that:
Ho 3+ the ion-doped fluoride crystal is Ho, LuLiF 4 (Ho: LLF) crystal or Ho: BaYF 4 (Ho: BYF) crystal or Ho: CaF 2 And (4) crystals.
Example 4
A 2 μm and 3 μm dual wavelength solid state mid-ir laser is provided according to example 1, with the difference that:
as shown in FIG. 6, the 2 μm and 3 μm dual-wavelength solid mid-infrared laser adopts a composite dual-cavity structure, the resonant cavity further comprises a 45-degree harmonic mirror 7, a laser output mirror B8 and a filter B9, the 45-degree harmonic mirror 7 is arranged at Ho 3+ Between the ion-doped laser crystal 4 and the laser output mirror A5, and the 45-degree harmonic mirror 7 and the light path form a 45-degree included angle; the laser output mirror B8 and the filter B9 are arranged on one side of the 45-degree harmonic mirror 7;
pumping light output by the 1150nm optical fiber laser passes through collimation of the collimation focusing system 2, then enters the Ho YLF crystal through the laser input mirror, and is pumped by the Ho YLF crystal; the 45-degree harmonic mirror 7 is highly transparent to 3 mu m laser and highly reflective to 2 mu m laser; laser input mirrors A3, Ho 3+ The ion-doped laser crystal 4 and the laser output mirror A5 form A3-micron resonant cavity to generate 3-micron laser, the 3-micron laser is coupled and output by the laser output mirror A5, and the filter A6 filters residual 1150nm pump light and outputs 3-micron mid-infrared laser; laser input mirrors A3, Ho 3+ The ion-doped laser crystal 4, the 45-degree harmonic mirror 7 and the laser output mirror B8 form a 2-micron resonant cavity to generate 2-micron laser, and the laser output mirror B8 forms a laser output mirrorAnd coupling and outputting, wherein a filter B9 filters residual 1150nm pump light and outputs mid-infrared laser with the wavelength of 2 mu m. By adopting the composite double-cavity structure, the cavity design can be optimized respectively for 2-micron laser and 3-micron laser, and the conversion efficiency, the output power and the beam quality are improved.
The angle a of the filter a6 and the light path satisfies 0 ° < a <10 °. The angle a of the filter B9 and the light path satisfies 0 ° < a <10 °.
The filter A6/the filter B9 are germanium sheets or harmonic lenses with evaporated dielectric films.
The laser input mirror A3, the laser output mirror A5 and the laser output mirror B8 are ZnSe crystals. The laser has higher transmittance for 2-micron and 3-micron mid-infrared lasers, reduces absorption loss, and simultaneously realizes the functions of positive feedback and mode selection of the resonant cavity.
The laser input mirror A3 is plated with a pumping light antireflection film and high reflection films with the wavelengths of 2 mu m and 3 mu m; the transmittance of the pump light antireflection film to 1150nm pump light is more than 95%, and the reflectivities of the high-reflection film to 2 mu m and 3 mu m wavelengths are more than 99.8%;
the 45-degree harmonic mirror 7 is plated with a 3-micron antireflection film and a 2-micron high-reflection film, the transmittance of the 45-degree harmonic mirror to the wavelength of 3 microns is more than 99.5%, and the reflectivity of the 45-degree harmonic mirror to the wavelength of 2 microns is more than 99.8%;
the laser output mirror A5 is coated with partial transmission films with the wavelengths of 2 μm and 3 μm, the transmittance of the partial transmission films with the wavelengths of 2 μm is more than 99.5 percent, and the transmittance of the partial transmission films with the wavelengths of 3 μm is 20 percent;
the laser output mirror B8 was coated with a 2 μm and 3 μm wavelength partially transmissive film with a 2 μm wavelength transmittance of 20% and a3 μm wavelength transmittance of greater than 99.5%.
The design of the composite cavity can realize the mode matching of the pump light and the oscillation light according to the gain of the 2 mu m laser and the 3 mu m laser and the size of the oscillation light spot in the lossy cavity, and improve the output power and the beam quality of the output 2 mu m laser and the 3 mu m laser.
Claims (10)
1. A2 μm and 3 μm dual-wavelength solid mid-infrared laser is characterized by comprising a pump laser, a collimation focusing system, a resonant cavity and a filter A which are sequentially arranged along a light path; the resonator cavity includes a laser input mirror A, Ho 3+ Ion(s)Doping a laser crystal and a laser output mirror A;
the pump laser is a semiconductor laser or a fiber Raman laser, and the working wavelength of the pump laser is 1120-1150 nm;
the Ho 3+ The ion-doped laser crystal is Ho 3+ Ion-doped fluoride crystals or Ho 3+ Ion-doped sesquioxide crystals;
after the pump light output by the pump laser is collimated by the collimating and focusing system, the pump light enters the resonant cavity, and the pump light enters the Ho after passing through the laser input mirror A 3+ Ion doping laser crystal, for the Ho 3+ Pumping the ion-doped laser crystal, forming optical cascade oscillation in the resonant cavity, generating mid-infrared laser with the wavelength of 2 microns and 3 microns, and coupling and outputting the mid-infrared laser by the laser output mirror A; the filter A filters out the residual pump light and outputs mid-infrared laser with the wavelength of 2 mu m and 3 mu m.
2. The 2 μm and 3 μm dual wavelength solid state mid-infrared laser as claimed in claim 1, wherein Ho is 3 + The doping concentration range of the ion-doped laser crystal is 0.5-1.5 at.%.
3. The 2 μm and 3 μm dual wavelength solid state mid-infrared laser as claimed in claim 1, wherein Ho is 3 + The ion-doped fluoride crystal is Ho: YLiF 4 Crystal, Ho LuLiF 4 Crystal, Ho: BaYF 4 Crystal, Ho: CaF 2 And (4) crystals.
4. The 2 μm and 3 μm dual wavelength solid state mid-infrared laser as claimed in claim 1, wherein the pump laser is a fiber raman laser with an output wavelength of 1150 nm.
5. The 2 μm and 3 μm dual-wavelength solid mid-infrared laser as claimed in claim 1, wherein the laser input mirror a is coated with a pump light antireflection film, a high reflection film of 2 μm and 3 μm wavelength; the transmittance of the pump light antireflection film to pump light is more than 95%, and the reflectivity of the high-reflection film to wavelengths of 2 mu m and 3 mu m is more than 99.8%;
the laser output mirror A is plated with partial transmission films with the wavelengths of 2 mu m and 3 mu m, the transmittance of the partial transmission films with the wavelengths of 2 mu m is 10-27%, and the transmittance of the partial transmission films with the wavelengths of 3 mu m is 10-38%.
6. A 2 μm and 3 μm dual wavelength solid state mid-ir laser as claimed in claim 1, further comprising a 45 ° harmonic mirror, a laser output mirror B and a filter B in the resonator, wherein the 45 ° harmonic mirror is disposed at the Ho 3+ The 45-degree harmonic mirror forms a 45-degree included angle with the light path between the ion-doped laser crystal and the laser output mirror A; the laser output mirror B and the filter plate B are sequentially arranged on one side of the 45-degree harmonic mirror;
laser input mirror A, Ho 3+ The ion-doped laser crystal and the laser output mirror A form a 3-micron resonant cavity to generate 3-micron laser, the 3-micron laser is coupled and output by the laser output mirror A, and the filter A filters residual pump light and outputs 3-micron wavelength mid-infrared laser;
laser input mirror A, Ho 3+ The ion-doped laser crystal, the 45-degree harmonic mirror and the laser output mirror B form a 2-micron resonant cavity to generate 2-micron laser, the 2-micron laser is coupled and output by the laser output mirror B, and the filter B filters residual pump light and outputs mid-infrared laser with the wavelength of 2 microns.
7. The 2 μm and 3 μm dual-wavelength solid mid-infrared laser as claimed in claim 6, wherein the laser input mirror A is coated with a pump light antireflection film, a high reflection film with 2 μm and 3 μm wavelength; the transmittance of the pump light antireflection film to the pump light is more than 95%, and the reflectivity of the high-reflection film to the wavelengths of 2 mu m and 3 mu m is more than 99.8%;
the 45-degree harmonic mirror is plated with a 3-micron anti-reflection film and a 2-micron high-reflection film, the transmittance of the 45-degree harmonic mirror to the wavelength of 3 microns is more than 99.5%, and the reflectivity of the 45-degree harmonic mirror to the wavelength of 2 microns is more than 99.8%;
the laser output mirror A is plated with partial transmission films with the wavelengths of 2 microns and 3 microns, the transmittance of the partial transmission films with the wavelengths of 2 microns is more than 99.5%, and the transmittance of the partial transmission films with the wavelengths of 3 microns is 20%;
the laser output mirror B is plated with partial transmission films with the wavelengths of 2 microns and 3 microns, the transmittance of the partial transmission films with the wavelengths of 2 microns is 20%, and the transmittance of the partial transmission films with the wavelengths of 3 microns is more than 99.5%.
8. The 2 μm and 3 μm dual-wavelength solid mid-infrared laser as claimed in claim 6, wherein the laser input mirror A, the laser output mirror B and the 45 ° harmonic mirror are made of calcium fluoride crystal or ZnSe crystal.
9. A2 μm and 3 μm dual wavelength solid mid IR laser according to claim 6, wherein the angle a of filter A/filter B to the optical path satisfies: 0 ° < a <10 °; the filter A/the filter B is a germanium sheet or a harmonic lens of a vapor deposition dielectric film.
10. A 2 μm and 3 μm dual wavelength solid state mid-infrared laser as claimed in claim 1, wherein the output mode of said semiconductor laser is one of free space direct output, fiber coupled output, stacked array output and linear array output.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116742463A (en) * | 2023-08-15 | 2023-09-12 | 长春理工大学 | Intermediate infrared laser of dual-wavelength pumping bonding crystal |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116742463A (en) * | 2023-08-15 | 2023-09-12 | 长春理工大学 | Intermediate infrared laser of dual-wavelength pumping bonding crystal |
| CN116742463B (en) * | 2023-08-15 | 2024-04-02 | 长春理工大学 | Intermediate infrared laser of dual-wavelength pumping bonding crystal |
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