CN114825024A - Method and system for efficiently acquiring mid-infrared pulse laser - Google Patents

Method and system for efficiently acquiring mid-infrared pulse laser Download PDF

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Publication number
CN114825024A
CN114825024A CN202210223763.7A CN202210223763A CN114825024A CN 114825024 A CN114825024 A CN 114825024A CN 202210223763 A CN202210223763 A CN 202210223763A CN 114825024 A CN114825024 A CN 114825024A
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laser
mid
energy level
infrared
infrared laser
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张帅一
徐建一
徐剑秋
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Jiangsu Xinglian Laser Technology Co ltd
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Jiangsu Xinglian Laser Technology Co ltd
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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
    • H01S3/16—Solid materials
    • H01S3/1601—Solid materials characterised by an active (lasing) ion
    • 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
    • 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
    • H01S3/09—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
    • H01S3/094076—Pulsed or modulated pumping
    • 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

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  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Optics & Photonics (AREA)
  • Lasers (AREA)

Abstract

The invention discloses a method and a system for efficiently acquiring mid-infrared pulse laser, belonging to the laser field, wherein the method is applied to an all-solid-state mid-infrared laser, a laser gain medium of the method comprises activated ions with a mid-infrared laser upper energy level, a mid-infrared laser lower energy level and a ground state energy level, and pumping laser emitted by a pumping light source of the method is used for pumping particles on the ground state energy level to the mid-infrared laser upper energy level so as to generate the mid-infrared laser when the particles jump from the mid-infrared laser upper energy level to the mid-infrared laser lower energy level, and the method comprises the following steps: inputting modulated laser which periodically changes to a laser gain medium in the working process of the all-solid-state intermediate infrared laser; the wavelength of the modulated laser light matches the wavelength of the laser light generated when the particle transitions from the mid-infrared laser lower energy level to the ground state energy level. The invention periodically modulates the particle number of the lower energy level of the mid-infrared laser by modulating the laser, and solves the problems of large loss, low conversion efficiency and instability of the infrared pulse laser in the traditional technology.

Description

Method and system for efficiently acquiring mid-infrared pulse laser
Technical Field
The invention relates to the technical field of laser, in particular to a method and a system for efficiently acquiring mid-infrared pulse laser.
Background
Due to the important transmission window covering the atmosphere, mid-infrared (e.g. 3 μm) lasers with high repetition frequency and high average power have important applications in environmental monitoring, national security, and medical diagnosis and treatment, and are currently the key technologies in urgent need of development.
The main methods for realizing mid-infrared (e.g. 3 μm) laser in the field of solid-state laser technology at present are optical parametric oscillators, fiber lasers and all-solid-state lasers. The most mature of the lasers is the optical parametric oscillator, and the output of the mid-infrared laser at room temperature can be realized because the problem of population inversion is not involved, but the obtained mid-infrared laser belongs to idle light, the conversion efficiency is low, the structure is complex, and the operability is poor. The fiber laser is easy to break, has low damage threshold value and is not beneficial to energy storage, and in addition, the matrix available for selecting the middle infrared band laser is less, so the fiber laser is not beneficial to the operation of the middle infrared (such as 3 mu m) laser, especially the output of the large-energy laser.
All-solid-state lasers producing mid-infrared (e.g., 3 μm) laser light are beginning to begin earlier, but are slow and inefficient. This is due to the low quantum efficiency of the conversion of short-wave pump light in the near infrared to long-wave laser light in the mid infrared. On the other hand, currently active ions (e.g., Er) capable of directly generating laser light of mid-infrared (e.g., 3 μm) band 3+ 、Ho 3+ 、Dy 3+ ) All belong to three-energy-level structures, and the service life of the laser lower-level particles is generally longer than that of the laser upper-level particles. By Ho 3+ For example, its lower laser energy level 5 I 7 Laser upper energy level of lifetime ratio 5 I 6 The service life is as long as 14ms (about), which greatly increases the difficulty of realizing population inversion of mid-infrared (e.g. 3 μm) laser, greatly improves the pumping threshold value, and affects the conversion efficiency. Meanwhile, because the current 3 μm laser lacks a mature and reliable Q-switch and a pumping source of the semiconductor laser with the wavelength of 1150nm is not mature, the high-efficiency 3 μm pulse laser output is difficult to obtain by adopting the traditional Q-switch modulation technology or pumping mode.
Therefore, the realization of high-efficiency mid-infrared solid pulse laser output is still a technical problem which needs to be solved urgently at present.
Disclosure of Invention
Aiming at the problems of high pumping threshold, low conversion efficiency and lack of mature Q-switch in the mid-infrared solid pulse laser technology in the prior art, the invention aims to provide a method and a system for efficiently acquiring mid-infrared pulse laser.
In order to achieve the purpose, the technical scheme of the invention is as follows:
in a first aspect, the present invention provides a method for acquiring mid-infrared pulsed laser with high efficiency, where the method is applied to an all-solid-state mid-infrared laser, where the all-solid-state mid-infrared laser includes a pump light source and a laser gain medium, the laser gain medium includes active ions, particles in the active ions have an upper mid-infrared laser level, a lower mid-infrared laser level, and a ground level, and pump laser light emitted by the pump light source is used to pump particles in the ground level to the upper mid-infrared laser level, so that the mid-infrared laser light is generated when the particles transition from the upper mid-infrared laser level to the lower mid-infrared laser level, where the method includes:
inputting modulated laser to the laser gain medium in the process that the all-solid-state intermediate infrared laser outputs intermediate infrared laser by receiving pump laser emitted by a pump light source;
the modulated laser is pulse signal laser which changes periodically, and the wavelength of the modulated laser is matched with the wavelength of the laser generated when the particles transit from the lower energy level of the mid-infrared laser to the ground state energy level.
Preferably, the activating ion is Ho 3+ The wavelength of the pump laser is 1150nm, the wavelength of the mid-infrared laser is 2.9 μm, and the wavelength of the modulated laser is 2 μm.
In a second aspect, the present invention further provides a system for obtaining mid-infrared pulse laser with high efficiency, including an all-solid-state mid-infrared laser, where the all-solid-state mid-infrared laser includes a pump light source and a laser gain medium, the laser gain medium includes active ions, particles in the active ions have an upper mid-infrared laser level, a lower mid-infrared laser level, and a ground level, the pump laser emitted by the pump light source is used to pump the particles on the ground level to the upper mid-infrared laser level, so that the particles generate mid-infrared laser when transitioning from the upper mid-infrared laser level to the lower mid-infrared laser level, and the system further includes a modulation laser, the modulation laser is used to output modulation laser that changes periodically, the modulation laser and the pump laser are combined by a beam combining device and then input to the laser gain medium together, and the wavelength of the modulation laser and the excitation generated when the particles transition from the lower mid-infrared laser level to the ground level are combined together, and the modulation laser and the excitation generated when the particles transition from the lower mid-infrared laser level to the ground level The wavelengths of the light are matched.
Preferably, the all-solid-state mid-infrared laser further includes a collimating lens, a condensing lens, and a front cavity mirror sequentially disposed between the pump light source and the laser gain medium, and further includes a rear cavity mirror located at the rear side of the laser gain medium.
Preferably, a microchannel cooling heat sink is arranged on the side wall of the laser gain medium.
Preferably, the beam combining device includes a plane mirror, the plane mirror is disposed between the pump light source and the laser gain medium, and the plane mirror has high transmittance for the pump laser and high reflectance for the modulated laser.
Preferably, the activating ion is Ho 3+ The laser gain medium is Ho-doped 3+ The host of the laser crystal is fluoride or sesquioxide with low phonon energy; the wavelength of the pump laser is 1150nm, the wavelength of the mid-infrared laser is 2.9 μm, and the wavelength of the modulated laser is 2 μm.
Preferably, the pump light source is a semiconductor laser pump source.
Preferably, the modulation laser is an all-solid-state laser or a fiber laser.
By adopting the technical scheme, the invention has the beneficial effects that: due to modulation of the wavelength of the laser and the particle mid-IR energy level: ( 5 I 7 ) To the ground state energy level ( 5 I 8 ) The wavelengths of the laser light generated during the transition are matched, which causes the transition to be at mid-redExternal laser lower energy level: ( 5 I 7 ) The particles on the surface are excited to radiate, thereby shortening the energy level of the particles under the middle infrared laser ( 5 I 7 ) The service life of the medium infrared laser is beneficial to realizing the population inversion of the medium infrared laser, so that the medium infrared laser is at the upper energy level ( 5 I 6 ) The particles on the surface can be more effectively excited to radiate and jump to the lower energy level of the intermediate infrared laser ( 5 I 7 ) And further generates intermediate infrared laser synchronous with the modulated laser, thereby solving the problems of large intermediate infrared laser loss, high pumping threshold and low conversion efficiency in the traditional intermediate infrared solid laser technology. When the modulated laser beam is a pulse signal laser beam, the output mid-infrared laser beam is also a pulse laser beam, and changes in a cycle having the same frequency as the modulated laser beam.
Drawings
FIG. 1 shows Ho in the first embodiment of the present invention 3+ A schematic diagram of particle energy level transition;
fig. 2 is a schematic diagram of a process for establishing a modulation laser-lower holmium-doped 2.9 μm laser in the first embodiment of the present invention;
FIG. 3 is a schematic structural diagram according to a second embodiment of the present invention;
FIG. 4 is a schematic structural diagram of a modulated laser according to a second embodiment of the present invention;
fig. 5 is a schematic structural diagram of a modulated laser according to a third embodiment of the present invention.
In the figure: 3.1-pumping light source, 3.2-collimating lens, 3.3-focusing lens, 3.4-front cavity mirror, 3.5-beam combining device, 3.6-micro-channel red copper upper heat sink, 3.7-micro-channel red copper lower heat sink, 3.8-laser gain medium, 3.9-rear cavity mirror, 3.10-modulation laser, 3.11-plano-convex lens, 4.1-pumping source A, 4.2-collimating lens A, 4.3-focusing lens B, 4.4-front cavity mirror A, 4.5-micro-channel red copper upper heat sink A, 4.6-micro-channel red copper lower heat sink A, 4.7-laser gain medium A, 4.8-Q switch A, 4.9-rear cavity mirror A, 5.1-pumping source B, 5.2-high-reflection fiber grating, 5.3-fiber beam combining device, 5.4-gain fiber, 5.5.5-Q switch B, 5.6-low reflection fiber grating.
Detailed Description
The following further describes embodiments of the present invention with reference to the drawings. It should be noted that the description of the embodiments is provided to help understanding of the present invention, but the present invention is not limited thereto. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
It should be noted that in the description of the present invention, the terms "upper", "lower", "left", "right", "front", "rear", and the like indicate orientations or positional relationships based on structures shown in the drawings, and are only used for convenience in describing the present invention, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention.
In the technical scheme, the terms "first" and "second" are only used for referring to the same or similar structures or corresponding structures with similar functions, and are not used for ranking the importance of the structures, or comparing the sizes or other meanings.
In addition, unless expressly stated or limited otherwise, the terms "mounted" and "connected" are to be construed broadly, e.g., the connection may be a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; the two structures can be directly connected or indirectly connected through an intermediate medium, and the two structures can be communicated with each other. To those skilled in the art, the specific meanings of the above terms in the present invention can be understood in light of the present general concepts, in connection with the specific context of the scheme.
Example one
A method for efficiently acquiring mid-infrared pulse laser is applied to an all-solid-state mid-infrared laser and is used for reducing the loss of the mid-infrared pulse laser and reducing a pumping threshold value, so that the conversion efficiency of the pumping laser is improved, and the stability is improved.
The all-solid-state intermediate infrared laser comprises a pumping light source and a laser gain medium, wherein the laser gain medium comprises active ions, and the active ions in the active ionsThe particles have a mid-infrared laser upper energy level of ( 5 I 6 ) Mid-infrared laser lower energy level ( 5 I 7 ) And the ground state energy level ( 5 I 8 ) 3 energy levels in total, the pump light source is used for emitting pump laser in near infrared band, and the pump laser is used for being positioned in 5 I 8 Pumping particles at energy level to 5 I 6 Energy level to facilitate particle separation from 5 I 6 Energy level direction 5 I 7 And generating middle infrared laser when the energy level is transited. However, because of the particles in 5 I 7 Ratio of lifetime at energy level 5 I 6 Long energy level lifetime to activate ion Ho 3+ For example, the service lives are respectively 16ms and 2ms, which greatly increases the difficulty of implementing population inversion of the existing all-solid-state mid-infrared laser, thereby increasing the pumping threshold and affecting the efficiency of converting the pumping laser into the mid-infrared laser. In addition, since the prior art mid-infrared pulse laser lacks a mature Q-switch, it is difficult to obtain a stable output of the mid-infrared pulse laser.
Based on this, the method of this embodiment includes:
inputting modulated laser to a laser gain medium in the process that an all-solid-state intermediate infrared laser outputs intermediate infrared laser by receiving pump laser emitted by a pump light source; wherein, the modulated laser is configured as a periodically-changed pulse signal laser on the one hand, and the wavelength and the particle mid-infrared laser lower energy level of the modulated laser on the other hand ( 5 I 7 ) To the ground state energy level ( 5 I 8 ) The wavelengths of the laser light generated at the transition are matched.
So arranged, by introducing the modulated laser, and making the wavelength and particles of the modulated laser lower energy level ( 5 I 7 ) To the ground state energy level ( 5 I 8 ) The wavelengths of the laser light generated during the transition are matched so as to be at the lower energy level of the mid-infrared laser light ( 5 I 7 ) The lower energy level of the particles under the middle infrared laser is greatly shortened by the stimulated radiation of the particles ( 5 I 7 ) The service life of the medium infrared laser is beneficial to realizing the population inversion of the medium infrared laser, so that the medium infrared laser is at the upper energy level (C) 5 I 6 ) The particles on the surface can be more effectively excited to radiate and jump to the lower energy level of the intermediate infrared laser ( 5 I 7 ) And further generates intermediate infrared laser synchronous with the modulated laser, thereby solving the problems of large intermediate infrared laser loss, high pumping threshold and low conversion efficiency in the traditional intermediate infrared solid laser technology.
For example, when the active ion is Ho 3+ When the laser gain medium is charged with pumping laser with a wavelength of 1150nm, the laser gain medium is in a state 5 I 8 The ground state particles at the energy level are pumped to 5 I 6 On an energy level, while the particles are selected from 5 I 6 Energy level direction 5 I 7 The mid-infrared laser generated during energy level transition has a wavelength of 2.9 μm (i.e. 3 μm mid-infrared laser), and the particle size is selected from 5 I 7 Energy level direction 5 I 8 The laser wavelength generated upon energy level transition is 2 μm, as shown in FIG. 1. Therefore, after modulated laser light having a wavelength of 2 μm (1900nm to 2200nm, i.e., a frequency close to each other) is inputted into the laser gain medium, the modulated laser light has a wavelength different from that of the particles 5 I 7 Energy level direction 5 I 8 The wavelength of the laser light generated during the energy level transition is matched, and therefore, in the case of frequency matching, this is caused 5 I 7 The particles at the energy level generate stimulated radiation, thereby acting as a pair 5 I 7 The loss of laser with the wavelength of 2.9 μm is indirectly reduced by the upper particle modulation of the energy level, thereby realizing the output of 2.9 μm laser with low threshold and high efficiency.
It will be appreciated that in other preferred embodiments, mid-infrared laser outputs at other wavelengths with low threshold and high efficiency can be achieved by changing the type of active ions and reselecting the pump laser and the modulated laser wavelength.
In addition, as shown in FIG. 2, it shows a schematic diagram of the setup process of pulse signal modulated laser holmium-doped 2.9 μm laser, since the wavelength and particle of the modulated laser are selected from 5 I 7 Energy level direction 5 I 8 The wavelengths of the laser light generated during the energy level transition are basically equivalent, so that the lower energy level of the mid-infrared laser light is ( 5 I 7 ) Number of particles n 1i Is modulated by pulse signalNumber of particles n of laser 2 Periodic modulation, modulated mid-infrared laser lower energy level: ( 5 I 7 ) Number of particles n 1t The periodicity is reduced, which is equivalent to increasing the inversion population of the mid-infrared laser, reducing losses, thereby reducing the pumping threshold of the mid-infrared laser, resulting in a low-threshold, high-efficiency mid-infrared laser output, as shown by the mid-infrared laser population Δ n in fig. 2.
As can be seen from fig. 2, the periodic variation law of the finally obtained mid-infrared laser is the same as the periodic variation law of the modulated laser, so that the mid-infrared laser with periodic variation can be obtained by inputting the modulated laser with periodic variation. Thereby bypassing the immature problem of the Q-switching technology of the infrared pulse laser in the prior art.
Example two
A system for efficiently harvesting mid-infrared pulsed laser light, as shown in fig. 3, includes an all-solid-state mid-infrared laser and a modulated laser. The all-solid-state intermediate infrared laser is used for outputting intermediate infrared laser, the modulation laser is used for outputting modulation laser which changes periodically, and the modulation laser is used for periodically modulating the particle number of the lower energy level of the intermediate infrared laser, so that the loss of the intermediate infrared laser is reduced, and the high-efficiency and high-power intermediate infrared pulse laser output is obtained.
The all-solid-state intermediate infrared laser comprises a pumping light source 3.1, a collimating lens 3.2, a condensing lens 3.3, a front cavity mirror 3.4, a laser gain medium 3.8 and a rear cavity mirror 3.9 which are sequentially arranged along a light path propagation path. Typically, micro-channel cooling heat sinks, such as a water-cooled micro-channel copper upper heat sink 3.6 and a micro-channel copper upper heat sink 3.7, are disposed on the upper and lower sidewalls of the laser gain medium 3.8, respectively.
The laser gain medium 3.8 includes active ions, e.g. Ho 3+ The particles in the active ion have a mid-infrared laser upper energy level ( 5 I 6 ) Mid-infrared laser lower energy level ( 5 I 7 ) And the ground state energy level ( 5 I 8 ) Correspondingly, the laser gain medium 3.8 is configured to be Ho-doped 3+ The laser crystal of (1), the laser crystal having a substrateOften a fluoride or sesquioxide with low phonon energy. The pump light source 3.1 is used for emitting pump laser light with a wavelength within an absorption peak of the laser gain medium 3.8, for example, the pump light source 3.1 is configured as a semiconductor laser with a central wavelength of 1150nm, and the emitted pump laser light is specifically used for setting a ground level ( 5 I 8 ) Upper particle pumping to mid-infrared laser upper energy level: ( 5 I 6 ) So that the particles are lasing at an energy level from the mid-infrared ( 5 I 6 ) Mid-infrared laser lower energy level ( 5 I 7 ) The transition generates intermediate infrared (2.9 μm) laser, and the particle also has a lower energy level (m) than the intermediate infrared laser 5 I 7 ) To the ground state energy level ( 5 I 8 ) The transition thus generates laser light of other wavelengths (3.9 μm).
However, due to the particles in 5 I 7 The ratio of the lifetime on the energy level (16 ms) is 5 I 6 The service life of the energy level (2 ms) is as long as 14ms, so that the difficulty of realizing population inversion of the existing all-solid-state mid-infrared laser is greatly increased, the pumping threshold is improved, and the efficiency of converting pumping laser into mid-infrared laser is influenced.
In this respect, the present embodiment configures the modulated laser 3.10 for outputting modulated laser light having a wavelength of 2 μm, for example 3.9 μm, which is combined with the above-mentioned pump laser light by the beam combining device 3.5 and input into the laser gain medium in such a way that the particles are guided from the laser gain medium 5 I 7 Energy level direction 5 I 8 The energy level transition generates stimulated radiation amplification, thereby playing a role in 5 I 7 The loss of laser with the wavelength of 2.9 μm is indirectly reduced by the upper particle modulation of the energy level, thereby realizing the output of 2.9 μm laser with low threshold and high efficiency. The beam combining device 3.5 is a plane reflector, the plane reflector is arranged between the front cavity mirror 3.4 and the laser gain medium 3.8, the plane reflector and the pump laser are obliquely arranged at an angle of 45 degrees, and the plane reflector is configured to have high transmission on the pump laser and high reflection on the modulation laser. And a plano-convex lens 3.11 for focusing is arranged between the modulation laser 3.10 and the beam combining device 3.5.
It will be appreciated that the mode selection is also performed for laser light around a wavelength of 2.9 μm by means of a resonator consisting of a front mirror 3.4 and a rear mirror 3.9, wherein the front mirror 3.4 is coated with a highly transparent film for the pump wavelength 1150nm and a highly reflective film for the laser light 2.9 μm, and the rear mirror 3.9 is coated with a highly reflective film for the pump wavelength 1150nm and a partially transparent film for the laser light 2.9 μm and a highly transparent film of 2 μm.
In this embodiment, the modulation laser 3.10 is specifically configured as an all-solid-state laser, and as shown in fig. 4, in order to realize output of pulse laser light of 2 μm, a semiconductor laser with a central wavelength of 792nm is used as a pump source a4.1, the central wavelength of which is within an absorption peak of a laser gain medium a4.7, and the laser gain medium a4.7 is coupled through a collimating lens a4.2 and a focusing lens a 4.3. Laser gain medium A4.7 is Tm 3+ And Ho 3+ Co-doped or singly doped Tm 3+ The laser crystal is cooled by a micro-channel red copper upper heat sink A4.5 and a micro-channel red copper lower heat sink A4.6 through water. The laser resonant cavity consists of a front cavity mirror A4.4 and a rear cavity mirror A4.9 and is used for feeding back and selecting a mode for laser near 2.0 mu m to generate laser with a specific wavelength, wherein the front cavity mirror A4.4 is plated with a high-transmission film with the pump light wavelength of 792nm and a high-reflection film with the laser of 2.0 mu m, and the rear cavity mirror A4.9 is plated with a high-reflection film with the pump light wavelength of 792nm and a partial-transmission film with the laser of 2.0 mu m. The Q switch A4.8 is placed in the resonant cavity and mainly used for modulating continuous laser and generating Q-switched laser output of 2.0 microns, the Q switch A4.8 can select an acousto-optic Q switch and can also select a saturable absorber, wherein the acousto-optic Q switch can determine the repetition frequency of pulse laser and can generate pulse laser modulation with high peak power, and the saturable absorber can realize low-cost compact pulse laser modulation.
By the arrangement, the problems of large intermediate infrared laser loss, high pumping threshold and low conversion efficiency in the traditional intermediate infrared solid laser technology can be solved; moreover, when the modulated laser is a pulse signal laser, the output mid-infrared laser is also a pulse laser, and the period of the output mid-infrared laser is changed with the same frequency as that of the modulated laser, so that the problem that the Q-switching technology of the mid-infrared laser is immature in the prior art can be solved, and the mid-infrared pulse laser can be obtained from another direction and angle.
EXAMPLE III
The difference from the second embodiment is that: in this embodiment, the modulation laser 3.10 is configured as a fiber laser, and as shown in fig. 5, in order to realize the output of the-2 μm fiber pulse laser, a semiconductor laser with a center wavelength of 792nm is used as a pump source B5.1, and the center wavelength thereof is located in the absorption peak of the gain fiber 5.4 and enters the gain fiber 5.4 through a 2 × 1 fiber combiner 5.3. The gain fiber 5.4 is a thulium or thulium holmium co-doped single mode fiber, the diameter of the fiber core is 10 μm, the numerical aperture NA is 0.09, and the diameter of the outer diameter of the fiber is 130 μm. The high reflection fiber grating 5.2 and the low reflection fiber grating 5.6 play the roles of resonant cavity laser oscillation and mode selection. Wherein the high-reflection fiber grating 5.2 is a high-reflection grating with the central wavelength of 2 μm, the reflectivity is more than 99 percent, the-3 dB bandwidth is 1nm, the supermode inhibition ratio is more than 10dB, and the high-reflection fiber grating plays a role of a front cavity mirror of a resonant cavity; the low reflection fiber grating 5.6 is a low reflection grating with the central wavelength of 2 mu m, the reflectivity is 10 percent, the-3 dB bandwidth is 1nm, the supermode inhibition ratio is more than 10dB, and the low reflection fiber grating plays a role of a resonant cavity output mirror. The optical combiner 5.3 couples 792nm pump light and 1960nm laser into the core of the gain fiber 5.4. The Q switch B5.5 is an optical fiber coupling acousto-optic modulator, is plated with a laser antireflection film of 2 mu m and is used for modulating continuous laser of 2 mu m to generate Q-switched pulse laser.
The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. It will be apparent to those skilled in the art that various changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, and the scope of protection is still within the scope of the invention.

Claims (9)

1. A method for acquiring mid-infrared pulse laser with high efficiency, which is applied to an all-solid-state mid-infrared laser, the all-solid-state mid-infrared laser comprises a pumping light source and a laser gain medium, the laser gain medium comprises activated ions, particles in the activated ions have a mid-infrared laser upper energy level, a mid-infrared laser lower energy level and a ground state energy level, the pumping light emitted by the pumping light source is used for pumping the particles on the ground state energy level to the mid-infrared laser upper energy level, so that the mid-infrared laser is generated when the particles transit from the mid-infrared laser upper energy level to the mid-infrared laser lower energy level, and the method is characterized in that: the method comprises the following steps:
inputting modulated laser to the laser gain medium in the process that the all-solid-state intermediate infrared laser outputs intermediate infrared laser by receiving pump laser emitted by a pump light source;
the modulated laser is pulse signal laser which changes periodically, and the wavelength of the modulated laser is matched with the wavelength of the laser generated when the particles transit from the lower energy level of the mid-infrared laser to the ground state energy level.
2. The method of claim 1, wherein: the active ion is Ho 3+ The wavelength of the pump laser is 1150nm, the wavelength of the mid-infrared laser is 2.9 μm, and the wavelength of the modulated laser is 2 μm.
3. A system for acquiring mid-infrared pulse laser with high efficiency, which comprises an all-solid-state mid-infrared laser, wherein the all-solid-state mid-infrared laser comprises a pumping light source and a laser gain medium, the laser gain medium comprises active ions, particles in the active ions have a mid-infrared laser upper energy level, a mid-infrared laser lower energy level and a ground state energy level, the pumping light emitted by the pumping light source is used for pumping the particles on the ground state energy level to the mid-infrared laser upper energy level, so that the mid-infrared laser is generated when the particles are transited from the mid-infrared laser upper energy level to the mid-infrared laser lower energy level, and the system is characterized in that: the laser gain control device comprises a modulation laser, wherein the modulation laser is used for outputting modulation laser which changes periodically, the modulation laser and the pumping laser are jointly input into a laser gain medium after being combined by a beam combining device, and the wavelength of the modulation laser is matched with the wavelength of laser generated when particles transit from an intermediate infrared laser lower energy level to a ground state energy level.
4. The system of claim 3, wherein: the all-solid-state intermediate infrared laser further comprises a collimating lens, a condensing lens and a front cavity mirror which are sequentially arranged between the pumping light source and the laser gain medium, and further comprises a rear cavity mirror positioned at the rear side of the laser gain medium.
5. The system of claim 4, wherein: and a micro-channel cooling heat sink is arranged on the side wall of the laser gain medium.
6. The system of claim 3, wherein: the beam combining device comprises a plane reflector, the plane reflector is arranged between the pump light source and the laser gain medium, and the plane reflector is highly transparent to the pump laser and highly reflective to the modulation laser.
7. The system of claim 3, wherein: the active ion is Ho 3+ The laser gain medium is Ho-doped 3+ The host of the laser crystal is fluoride or sesquioxide with low phonon energy; the wavelength of the pump laser is 1150nm, the wavelength of the mid-infrared laser is 2.9 μm, and the wavelength of the modulated laser is 2 μm.
8. The system of claim 7, wherein: the pumping light source is a semiconductor laser pumping source.
9. The system of claim 7, wherein: the modulation laser is an all-solid-state laser or a fiber laser.
CN202210223763.7A 2022-03-07 2022-03-07 Method and system for efficiently acquiring mid-infrared pulse laser Pending CN114825024A (en)

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