CN113193469A - Laser amplifier - Google Patents
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- CN113193469A CN113193469A CN202110466785.1A CN202110466785A CN113193469A CN 113193469 A CN113193469 A CN 113193469A CN 202110466785 A CN202110466785 A CN 202110466785A CN 113193469 A CN113193469 A CN 113193469A
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- 230000003287 optical effect Effects 0.000 claims abstract description 59
- 230000003321 amplification Effects 0.000 claims abstract description 45
- 238000003199 nucleic acid amplification method Methods 0.000 claims abstract description 45
- 238000005086 pumping Methods 0.000 claims abstract description 43
- 239000013078 crystal Substances 0.000 claims description 19
- 238000010521 absorption reaction Methods 0.000 claims description 6
- 239000013307 optical fiber Substances 0.000 claims description 4
- 229910052594 sapphire Inorganic materials 0.000 claims description 4
- 239000010980 sapphire Substances 0.000 claims description 4
- 229910009372 YVO4 Inorganic materials 0.000 claims description 3
- 238000003384 imaging method Methods 0.000 abstract description 3
- 230000000694 effects Effects 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 239000000835 fiber Substances 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- COQOFRFYIDPFFH-UHFFFAOYSA-N [K].[Gd] Chemical compound [K].[Gd] COQOFRFYIDPFFH-UHFFFAOYSA-N 0.000 description 1
- JNDMLEXHDPKVFC-UHFFFAOYSA-N aluminum;oxygen(2-);yttrium(3+) Chemical compound [O-2].[O-2].[O-2].[Al+3].[Y+3] JNDMLEXHDPKVFC-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 239000004973 liquid crystal related substance Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- LXRWZZFNYNSWPB-UHFFFAOYSA-N potassium yttrium Chemical compound [K].[Y] LXRWZZFNYNSWPB-UHFFFAOYSA-N 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000002207 thermal evaporation Methods 0.000 description 1
- QWVYNEUUYROOSZ-UHFFFAOYSA-N trioxido(oxo)vanadium;yttrium(3+) Chemical compound [Y+3].[O-][V]([O-])([O-])=O QWVYNEUUYROOSZ-UHFFFAOYSA-N 0.000 description 1
- 229910019901 yttrium aluminum garnet Inorganic materials 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
- H01S3/08—Construction or shape of optical resonators or components thereof
- H01S3/081—Construction or shape of optical resonators or components thereof comprising three or more reflectors
- H01S3/0813—Configuration of resonator
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
- H01S3/08—Construction or shape of optical resonators or components thereof
- H01S3/08059—Constructional details of the reflector, e.g. shape
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- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Plasma & Fusion (AREA)
- Optics & Photonics (AREA)
- Lasers (AREA)
Abstract
The application discloses a laser amplifier. The laser amplifier includes: a pumping optical path and a laser amplification optical path; the pumping optical path and the laser amplification optical path also jointly contain a laser gain medium. The folding light path in the laser amplifier reduces the overall structural size of the amplifier, and is convenient to install and use. The pump light passes through the laser gain medium twice, so that the utilization rate of the pump light is improved. In addition, due to the fact that the thermal lens imaging system is introduced into the laser amplifier, the wavefront distortion influence introduced by the device is reduced, and therefore the beam quality of the output laser is improved.
Description
Technical Field
The present application relates to the field of optical technology, and in particular, to a laser amplifier.
Background
With the development of laser processing technology, laser is increasingly applied to processing of materials such as metal, glass, sapphire, Liquid Crystal Display (LCD) panel, Organic Light-Emitting Diode (OLED) panel, and the like. Compared with the traditional mechanical processing, the laser processing has the characteristics of strong adaptability, clean processing, higher processing precision, no contact and the like, and along with the development of the industry, such as the change of the characteristics of higher and higher occupation ratio of a mobile phone screen, the requirements on the laser processing technology are higher and higher, and compared with the traditional nanosecond or continuous laser, the ultrafast laser generates less residual heat and is more suitable for fine processing.
The hybrid Amplifier based on the Master Oscillator Power-Amplifier (MOPA) is widely applied in the industrial field, on one hand, the scheme can realize that the signal light of the Oscillator with lower Power is injected into the Master Amplifier, and the signal light can be scaled and amplified to 100 muj or even mJ magnitude, and in addition, the scheme is combined with the reliability structure of the optical fiber seeds, so that the output of the amplified laser pulse is more reliable while ensuring high energy.
For ultrafast laser of sub picosecond or hundred femtosecond magnitude, the repetition frequency generated by the commonly used fiber mode-locked main oscillator is generally between 20-80MHz, and the repetition frequency is higher and the pulse width is narrower at the moment, so that the repetition frequency is not suitable for being directly injected into the subsequent main amplification stage, for this purpose, the repetition frequency of the signal light is generally reduced to 100KHz to 1MHz magnitude by using an acousto-optic crystal, then the pulse width is widened to hundreds picoseconds magnitude by using a solid offner structure or a fiber CFBG grating, and then the processed signal light is injected into the main amplification stage for energy amplification. To ensure the amplified pulse width, it is often necessary to select a crystal with sufficient gain bandwidth as the gain material. In addition, the amplifier generally has a relatively high output power, so that a specific crystal and a thermal deposition structure need to be selected to ensure good internal thermal gradient in the crystal amplification process so as to obtain a good beam quality output.
For the amplifier in the current ultrafast laser, the following problems are often existed:
the structure is complex, the occupied area is large, and the installation and the use are inconvenient; the utilization efficiency of the pump light is low; the introduction of a large number of lens and other body structures causes serious wavefront distortion and affects the output quality of laser.
Disclosure of Invention
Based on the above problem, this application provides a laser amplifier to reduce the structure size of amplifier, promote the utilization ratio of pump light, promote the output quality of laser.
The embodiment of the application discloses the following technical scheme:
the application provides a laser amplifier, including: a pumping optical path and a laser amplification optical path; wherein the device in the pump optical path comprises: the device comprises a pumping light source, a first group of lenses, a first group of reflectors, a second group of lenses, a third group of lenses and a second group of reflectors; the device in the laser amplification light path comprises: a fourth group of lenses and a third group of mirrors; the pumping optical path and the laser amplification optical path also jointly contain a laser gain medium; the laser gain medium is arranged between the second group of lenses and the third group of lenses;
in the pump optical path, the first group of lenses is used for collimating the pump light emitted by the pump light source to the first group of mirrors; the first group of reflectors are used for reflecting the collimated pump light emitted by the first group of lenses to the second group of lenses; the second group of lenses is used for focusing and transmitting the received pump light to the laser gain medium so that the pump light is absorbed by the laser gain medium for the first time; after the first absorption, the pump light transmitted from the laser gain medium is firstly collimated by the third group of lenses, then reflected by the second group of reflectors in the original way, focused by the third group of lenses, and then re-injected into the laser gain medium to be secondarily absorbed by the laser gain medium;
the fourth group of lenses includes: an incident end lens and an exit end lens; in the laser amplification light path, laser enters from the incident end lens, passes through the laser gain medium for multiple times under the action of the third group of reflectors, and finally exits from the exit end lens to finish amplification of laser power.
Optionally, the third set of mirrors comprises: a first mirror and a second mirror;
the first reflector is used for turning back the laser in the vertical direction emitted from the laser gain medium to the second reflector along the horizontal direction;
the second reflector is used for reflecting the laser light from the first reflector in the vertical direction so that the laser light is transmitted to the laser gain medium again.
Optionally, the third set of mirrors is entirely movable in a vertical direction;
the position of the third group of reflectors moves up and down according to the power of the pump light; the size of the optical power influences the focal length of a thermal lens equivalent to the laser gain medium; the power of the pump light is reduced, the focal length of the thermal lens is increased, and the third group of reflectors move upwards along the vertical direction to increase the optical path; the pump light power is increased, the thermal lens focal length is reduced, and the third group of reflectors move downwards along the vertical direction to reduce the optical path.
Optionally, the laser amplifier further comprises a first set of dichroic mirrors; two dichroic mirrors in the first group of dichroic mirrors are arranged in the pumping light path in a splayed structure, the two dichroic mirrors are positioned on two sides of the second group of lenses, and the first group of dichroic mirrors are used for pumping light with shorter wavelength and laser with longer wavelength; the dichroic mirror far away from the pump light source is used for transmitting pump light and reflecting laser, and the dichroic mirror close to the pump light source is used for further reflecting the laser transmitted out of the dichroic mirror far away from the pump light source.
Optionally, the laser amplifier further includes a second group of dichroic mirrors and a third group of dichroic mirrors;
the second group of dichroic mirrors are arranged between the laser gain medium and the third group of lenses and are used for transmitting pump light and reflecting laser;
the third group of dichroic mirrors are arranged between the third group of lenses and the second group of reflectors and are used for transmitting the pump light and further reflecting the laser light which penetrates through the second group of dichroic mirrors;
the second group of dichroic mirrors comprise a first dichroic mirror and a second dichroic mirror, and the third group of dichroic mirrors comprise a third dichroic mirror and a fourth dichroic mirror; the first dichroic mirror and the third dichroic mirror are arranged in an inverted-V-shaped structure in the upper half part of the optical path of the pumping optical path in the vertical direction; the second dichroic mirror and the fourth dichroic mirror are arranged in a splayed structure in the lower half portion of the pumping optical path in the vertical direction.
Optionally, the laser enters from the incident end lens, and the laser passes through the laser gain medium for multiple times under the action of the third group of reflecting mirrors and the second group of dichroic mirrors, and finally exits from the exit end lens.
Optionally, the laser gain medium equivalent thermal lens is confocal with the fourth group of lenses, and an optical path through which the laser passes from the end of the second-pass amplification to the beginning of the third-pass amplification of the laser gain medium is twice the focal length of the thermal lens.
Optionally, the pumping light source includes a plurality of point-shaped light source units;
the first group lens, the second group lens, and the third group lens each include lens units matching the number and positions of the light source units.
Alternatively, the lens units in the same group of lenses are separate lenses or are located in the same lens array.
Optionally, the distance between the end face of the laser gain medium and the second group of lenses is matched with the focal length of the second group of lenses; the size of the pumping light spot on the laser gain medium is related to the focal length of the first group of lenses, the focal length of the second group of lenses and the diameter of the pumping light output optical fiber.
Optionally, the second group of mirrors are horizontal mirrors, and are configured to turn back the pump light along the horizontal direction.
Optionally, the laser gain medium includes any one of:
yb is YAG crystal, Nd is YVO4 crystal, Yb is KGW crystal, Yb is KYW crystal or Ti is sapphire crystal.
Optionally, the laser passes 4 or more times through the laser gain medium.
Optionally, the first set of mirrors comprises: a reflective prism and/or a plane mirror.
Compared with the prior art, the method has the following beneficial effects:
the application provides a laser amplifier including: a pumping optical path and a laser amplification optical path; wherein the device in the pump optical path comprises: the device comprises a pumping light source, a first group of lenses, a first group of reflectors, a second group of lenses, a third group of lenses and a second group of reflectors; the device in the laser amplification light path comprises: a fourth group of lenses and a third group of mirrors; the pumping optical path and the laser amplification optical path also jointly contain a laser gain medium; the laser gain medium is arranged between the second group of lenses and the third group of lenses; in the pumping optical path, a first group of lenses is used for collimating the pumping light emitted by the pumping light source to a first group of reflectors; the first group of reflectors are used for reflecting the collimated pump light emitted by the first group of lenses to the second group of lenses; the second group of lenses are used for focusing and transmitting the received light to the laser gain medium so that the pump light is absorbed by the laser gain medium for the first time; after the first absorption, the pump light transmitted from the laser gain medium is transmitted by the third group of lenses, reflected by the second group of reflectors, transmitted by the third group of lenses again, reenters the laser gain medium and is absorbed by the laser gain medium for the second time; the fourth group of lenses includes: an incident end lens and an exit end lens; in the laser amplification light path, laser enters from the incident end lens, passes through the laser gain medium for multiple times under the action of the third group of reflectors, and finally exits from the exit end lens to finish the amplification of laser power.
The folded optical path in the laser amplifier provided in the application enables the overall structure size of the amplifier to be reduced, and the laser amplifier is convenient to install and use. The pump light passes through the laser gain medium twice, so that the utilization rate of the pump light is improved. In addition, a thermal lens imaging system is introduced into the laser amplifier by means of the laser gain medium, the third group of reflectors and the fourth group of lenses, so that the wavefront distortion influence introduced by the device is reduced, and the beam quality of output laser is improved.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without inventive exercise.
Fig. 1 is a schematic structural diagram of a laser amplifier according to an embodiment of the present application.
Detailed Description
The amplifier in the current ultrafast laser usually needs to introduce a larger number of lenses, and the convex surface or the concave surface realizes the beam deflection. Therefore, the quality of amplified laser output is affected by introducing more distortion to the whole structure inevitably. In addition, the laser amplifier has a large structure and is inconvenient to install and use. Further, the utilization rate of the pump light is low, and the pump light cannot be sufficiently utilized.
In view of the above problems, the inventors have studied to provide a novel laser amplifier structure. Wherein the cross section of the laser gain medium is rectangular, and the thickness of the laser gain medium is very thin and is below 1mm or 1 mm. The structure is compact, the utilization rate of pump light is higher, the introduction of wavefront distortion is reduced, and the beam quality after laser amplification is ensured.
In order to make the technical solutions of the present application better understood, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
Referring to fig. 1, the figure is a schematic structural diagram of a laser amplifier provided in an embodiment of the present application. In order to facilitate understanding of the function of the laser amplifier, the laser amplifier is divided into a pumping optical path and a laser amplification optical path. The pumping optical path refers to an optical path that the pumping light passes through, and the laser amplification optical path refers to an optical path that the laser to be amplified passes through. And a plurality of devices are respectively arranged on the pumping optical path and the laser amplification optical path. The following are described separately. In fig. 1, the gray light path represents a pumping light path, and the black light path represents a laser amplification light path.
The device in the pump optical path comprises: the optical lens comprises pump light sources 1-1 to 1-4, first groups of lenses 2-1 to 2-4, first groups of reflectors 3-1 to 3-4, second groups of lenses 5-1 to 5-4, third groups of lenses 8-1 to 8-4 and second groups of reflectors 9-1 to 9-4.
The device in the laser amplification light path comprises: a fourth set of lenses 11-1 and 11-2 and a third set of mirrors 10-1 and 10-2.
As shown in fig. 1, the pump optical path and the laser amplification optical path also together comprise a laser gain medium 6. The laser gain medium 6 includes any one of:
yb is YAG (ytterbium-doped yttrium aluminum garnet) crystal, Nd is YVO4 (neodymium-doped yttrium vanadate) crystal, Yb is KGW (ytterbium-doped gadolinium potassium tungstate) crystal, Yb is KYW (ytterbium-doped yttrium potassium tungstate) crystal or Ti is sapphire crystal. The embodiment of the present application does not limit the specific material of the laser gain medium 6.
The laser gain medium 6 is arranged between the second set of lenses 5-1 to 5-4 and the third set of lenses 8-1 to 8-4. If the laser amplification optical path is flattened, the laser gain medium 6 is equivalently arranged between the fourth group of lenses 11-1 and 11-2 and the third group of reflectors 10-1 and 10-2.
The pump light sources 1-1 to 1-4 can be semiconductor lasers, the pump light emitted by which is coupled out by means of optical fibers. The light emitted by a semiconductor laser is usually divergent light, and in order to apply the pump light as efficiently as possible, the pump light needs to be collimated. In the pump light path, the first group of lenses 2-1 to 2-4 is thus used to collimate the pump light emitted by the pump light sources 1-1 to 1-4. The first group of mirrors 3-1 to 3-4 function to divert the optical path, and the first group of mirrors 3-1 to 3-4 are used to reflect the collimated pump light emitted from the first group of lenses 2-1 to 2-4 to the second group of lenses 5-1 to 5-4. The light paths reflected from the first set of mirrors 3-1 to 3-4 are parallel to each other.
The second set of lenses 5-1 to 5-4 is used to focus the received light onto the laser gain medium 6 such that the pump light is absorbed by the laser gain medium 6 for the first time. The laser gain medium 6 may be equivalent to a thermal lens. The pump light transmitted from the laser gain medium 6 after the first absorption is firstly collimated by the third group of lenses 8-1 to 8-4, then reflected by the second group of reflectors 9-1 to 9-4 to return in the original path, and then the pump light returning along the original path is refocused by the third group of lenses 8-1 to 8-4 and then is sent into the laser gain medium 6 again to be absorbed by the laser gain medium 6 for the second time. As shown in fig. 1, the second set of mirrors 9-1 to 9-4 may be horizontal mirrors, i.e. may be used to fold the pump light back in a horizontal direction. In practice, the function of the mirrors 9-1 to 9-4 can also be performed by one monolithic mirror. The number of mirrors included in the second set of mirrors is not limited herein. To ensure that the pump light is uniformly absorbed during the second absorption, a second set of mirrors (if multiple mirrors are included) may be required to be disposed in the same plane.
The laser gain medium 6 generates energy level particle inversion after absorbing the pump light, then the incident laser is focused and then is injected into the laser gain medium 6, and the laser gain medium 6 is amplified by stimulated radiation, so that the power amplification can be completed. The fourth group of lenses shown in fig. 1 includes: an incident end lens 11-2 and an exit end lens 11-1. In the laser amplification light path, collimated laser enters from the incident end lens 11-2, and the incident end lens 11-2 plays a focusing role. The focused laser is irradiated on the laser gain medium 6, the thermal lens equivalent to the laser gain medium 6 is confocal with the incident end lens 11-2, and simultaneously the thermal lens equivalent to the laser gain medium 6 is also confocal with the emergent end lens 11-1.
In addition, the third group of mirrors in the embodiments of the present application includes: a first mirror 10-1 and a second mirror 10-2. The normals of the first mirror 10-1 and the second mirror 10-2 are perpendicular to each other, and the laser light incident on the first mirror 10-1 and the laser light reflected from the second mirror 10-2 are parallel to each other. The first reflector 10-1 is used for turning back the laser in the vertical direction emitted from the laser gain medium 6 to the second reflector 10-2 along the horizontal direction; the second mirror 10-2 is used to reflect the laser light from the first mirror 10-1 in the vertical direction so that the laser light is transmitted to the laser gain medium 6 again. That is, the third set of mirrors functions to enable multiple passes of the laser light in the laser gain medium 6 by the folded design.
For the four-pass laser amplification structure shown in fig. 1: the first pass is amplified, the focal length of the thermal lens of the laser gain medium 6 is confocal with the incident end lens 11-2, namely the distance between the right end surface of the laser gain medium 6 and the incident end lens 11-2 is approximately equal to the sum of the thermal focal length of the laser gain medium 6 and the focal length of the incident end lens 11-2, and the size of the focal length of the incident end lens 11-2 depends on the diameter of an incident laser beam and the diameter of pump light. Before the second pass amplification, the laser collimated by the thermal lens effect is folded by the dichroic mirrors 7-1 and 7-2 and then is irradiated onto the laser gain medium 6 again, the laser before the third pass amplification is irradiated onto the laser gain medium 6 again by the third group of reflectors 10-1 and 10-2 and the dichroic mirror 4-2, the distance from the second pass to the third pass laser gain medium 6 from the laser gain medium 6 is exactly equal to twice the thermal focal length of the equivalent thermal lens of the laser gain medium 6, a thermal lens auto-imaging system is formed, the output light of the laser after the third pass amplification is still collimated light due to the thermal lens effect, then the laser after the third pass amplification is incident into the laser gain medium 6 again by the dichroic mirrors 7-2 and 7-1 to complete the fourth pass amplification, and finally the output laser is imaged by the exit end lens 11-1 and then is collimated and output, and completing the amplification of the laser power.
In practical applications, in order to amplify the laser light in the laser gain medium 6 more times, the number of the lenses in the third set of reflecting mirrors and/or the second set of dichroic mirrors may be increased, or other positions may be changed. The specific implementation form of the third set of reflecting mirrors and the second set of dichroic mirrors and the number of the lenses therein are not limited herein.
The adjustable implementation of the third set of mirrors is described below in connection with the third set of mirrors shown in fig. 1. The third group of mirrors is movable in the vertical direction as a whole (i.e., vertically upward and downward in fig. 1). The positional shift of the third group of mirrors 10-1 and 10-2 is affected by the optical power of the pump light and moves up and down according to the power of the pump light. Specifically, the magnitude of the optical power affects the focal length of the thermal lens equivalent to the laser gain medium 6; the power of the pump light is reduced, the focal length of the thermal lens is increased, and the third group of mirrors 10-1 and 10-2 move upwards along the vertical direction to increase the optical path; the pump light power increases, the thermal lens focal length decreases, and the third group of mirrors 10-1 and 10-2 moves downward in the vertical direction to reduce the optical path length. The third group of reflectors which are arranged in the laser amplifier and can move in the vertical direction can be suitable for scenes with variable or unstable pump light power. Namely, the setting position of the third group of reflectors can be adjusted along with the pump light, so that a better and more stable laser amplification effect is achieved.
In the laser amplifiers involved in the prior art, the high power pump light is poorly safely isolated from the laser. The laser often causes some damage to the pump light source. In the embodiment of the present application, the pump light can be absorbed twice in the laser gain medium 6, and the pump light emitted from the laser gain medium 6 after the second absorption is very little, so that it is difficult to return to the pump light sources 1-1 to 1-4 to damage the pump light sources 1-1 to 1-4.
In addition, the dichroic mirror in the embodiments of the present application can allow light of a specific wavelength band to transmit and reflect light waves of another specific wavelength band. The dichroic mirror allows the pump light to pass through and reflects the laser light. Still referring to fig. 1. As shown in fig. 1, the laser amplifier also includes a first set of dichroic mirrors 4-1 and 4-2. The dichroic mirrors 4-1 and 4-2 are arranged in the pumping light path in a splayed structure, and the two dichroic mirrors are positioned at two sides of the second group of lenses 5-1 to 5-4, wherein one dichroic mirror 4-2 far away from the pumping light source is used for transmitting pumping light to reflect laser, and one dichroic mirror 4-1 close to the pumping light source is used for transmitting pumping light and reflecting laser leaking through the dichroic mirror 4-2.
Optionally, the dichroic mirror 4-1 and the dichroic mirror 4-2 are symmetrically arranged with respect to the second group of lenses 5-1 to 5-4. The dichroic mirrors have the same parameters and the pump light passing through the dichroic mirror 4-1 may be shifted by a certain amount, e.g. by x, downwards. The dichroic mirror 4-2 arranged in the splay structure can correct the original downward deviation upwards, namely, compensate the downward deviation x, so that the pump light incident to the dichroic mirror 4-1 and the pump light transmitted from the dichroic mirror 4-2 are collinear, and the pump light is kept unchanged in the front-back direction of the first group of dichroic mirrors 4-1 and 4-2.
Optionally, the laser amplifier provided in the embodiment of the present application further includes a second group of dichroic mirrors 7-1 and 7-2, and a third group of dichroic mirrors 7-3 and 7-4. As shown in fig. 1, the second group of dichroic mirrors 7-1 and 7-2 are disposed between the laser gain medium 6 and the third group of lenses 8-1 to 8-4 for transmitting the pump light and reflecting the laser light; the third group of dichroic mirrors 7-3 and 7-4 are arranged between the third group of lenses 8-1 to 8-4 and the second group of mirrors 9-1 to 9-4 for transmitting the pump light and reflecting the laser light leaking through the dichroic mirrors 7-1 and 7-2.
The second group of dichroic mirrors comprise a first dichroic mirror 7-1 and a second dichroic mirror 7-2, and the third group of dichroic mirrors comprise a third dichroic mirror 7-3 and a fourth dichroic mirror 7-4; the first dichroic mirror 7-1 and the third dichroic mirror 7-3 are arranged in the upper half part of the optical path of the pumping optical path in the vertical direction in an inverted splayed structure; the second dichroic mirror 7-2 and the fourth dichroic mirror 7-4 are arranged in a splayed structure in the lower half part of the pumping optical path in the vertical direction. In fig. 1, four beams of pump light are taken as an example, and the two beams of pump light in the upper half portion pass through the first dichroic mirror 7-1 and the third dichroic mirror 7-3 in sequence twice by combining the positions of the dichroic mirrors set in the figure; the two pumping light beams at the lower half part pass through the second dichroic mirror 7-2 and the fourth dichroic mirror 7-4 successively twice.
Alternatively, the first dichroic mirror 7-1 and the third dichroic mirror 7-3 are symmetrically disposed about the third group lenses 8-1 to 8-2. The second dichroic mirror 7-2 and the fourth dichroic mirror 7-4 are symmetrically disposed about the third group lenses 8-3 to 8-4. Similar to the effect of the first group of dichroic mirrors 4-1 and 4-2, the inverted-splayed-structure placement mode of the first dichroic mirror 7-1 and the third dichroic mirror 7-3 and the splayed-structure placement mode of the second dichroic mirror 7-2 and the fourth dichroic mirror 7-4 can correct the offset of the pump light in the light path, and prevent the light path from obviously offsetting before and after entering the dichroic mirrors.
In the embodiment of the application, the pump light with the shorter wavelength is effectively separated from the laser with the longer wavelength through the arrangement of the dichroic mirror, and the probability that the laser damages the pump light sources 1-1 to 1-4 is reduced to a certain extent, so that the purpose of protecting the pump light sources 1-1 to 1-4 is achieved, and the safe isolation of the pump light sources 1-1 to 1-4 and the laser is realized.
Unlike the conventional long pumping light source, in the embodiment of the present application, the pumping light source includes a plurality of point-like light source units 1-1 to 1-4. Fig. 1 illustrates only 4 light source units, and in practical applications, other numbers of light source units may be adopted. As shown in fig. 1, the first group lens, the second group lens, and the third group lens each include lens units whose number matches the number of light source units, and the first group lens, the second group lens, and the third group lens each include lens units whose positions match the positions of the light source units. The lens units in the same group of lenses may be separate lenses or may be located in the same lens array. Taking the first group of lenses as an example, the four lens units 2-1 to 2-4 are in the same lens array.
In the laser amplifier shown in fig. 1, the laser light passes 4 times through the laser gain medium 6. Namely, laser enters and focuses from the incident end lens 11-2 and is reflected to the laser gain medium 6 by the dichroic mirror 4-2; the laser light is emitted from the laser gain medium 6 to reach the first dichroic mirror 7-1, is reflected to the second dichroic mirror 7-2 by the first dichroic mirror 7-1, and is reflected to the laser gain medium 6 by the second dichroic mirror 7-2, so that the laser light passes through the laser gain medium 6 for the second time. And then, the laser is emitted from the laser gain medium 6 to reach the dichroic mirror 4-2, and is reflected by the dichroic mirror 4-2 to the first reflecting mirror 10-1, the second reflecting mirror 10-2 and the dichroic mirror 4-2 to reach the laser gain medium 6. The laser light is emitted from the laser gain medium 6 for the third time, reaches the second dichroic mirror 7-2, is reflected by the second dichroic mirror 7-2 and the first dichroic mirror 7-1 in sequence, and enters the laser gain medium 6 again. The laser is emitted from the laser gain medium 6 for the fourth time and then reaches the dichroic mirror 4-2, and is reflected to the emitting end lens 11-1 by the dichroic mirror 4-2. The exit end lens 11-1 emits the laser beam, i.e. forms a collimated laser beam after power amplification. Of course, in practical applications, the laser light may also pass through the laser gain medium 6 more than 4 times or less than 4 times by providing different numbers and/or different positions of the mirrors. The number of laser amplification passes is not limited here.
In the laser amplifier shown in fig. 1 in the embodiment of the present application, the first set of mirrors includes 4 reflection prisms 3-1 to 3-4. Of course, the implementation of the reflection function is not limited to the reflection prism, but may also be a circular or square plane mirror, for example. That is, the first set of mirrors may include only the reflecting prism, only the plane mirror, and may also include both the reflecting prism and the plane mirror in a mixed manner.
The above description is only one specific embodiment of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present application should be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (14)
1. A laser amplifier, comprising: a pumping optical path and a laser amplification optical path; wherein the device in the pump optical path comprises: the device comprises a pumping light source, a first group of lenses, a first group of reflectors, a second group of lenses, a third group of lenses and a second group of reflectors; the device in the laser amplification light path comprises: a fourth group of lenses and a third group of mirrors; the pumping optical path and the laser amplification optical path also jointly contain a laser gain medium; the laser gain medium is arranged between the second group of lenses and the third group of lenses;
in the pump optical path, the first group of lenses is used for collimating the pump light emitted by the pump light source to the first group of mirrors; the first group of reflectors are used for reflecting the collimated pump light emitted by the first group of lenses to the second group of lenses; the second group of lenses is used for focusing and transmitting the received pump light to the laser gain medium so that the pump light is absorbed by the laser gain medium for the first time; after the first absorption, the pump light transmitted from the laser gain medium is firstly collimated by the third group of lenses, then reflected by the second group of reflectors in the original way, focused by the third group of lenses, and then re-injected into the laser gain medium to be secondarily absorbed by the laser gain medium;
the fourth group of lenses includes: an incident end lens and an exit end lens; in the laser amplification light path, laser enters from the incident end lens, passes through the laser gain medium for multiple times under the action of the third group of reflectors, and finally exits from the exit end lens to finish amplification of laser power.
2. The laser amplifier of claim 1, wherein the third set of mirrors comprises: a first mirror and a second mirror;
the first reflector is used for turning back the laser in the vertical direction emitted from the laser gain medium to the second reflector along the horizontal direction;
the second reflector is used for reflecting the laser light from the first reflector in the vertical direction so that the laser light is transmitted to the laser gain medium again.
3. The laser amplifier of claim 2, wherein the third set of mirrors is entirely movable in a vertical direction;
the position of the third group of reflectors moves up and down according to the power of the pump light; the size of the optical power influences the focal length of a thermal lens equivalent to the laser gain medium; the power of the pump light is reduced, the focal length of the thermal lens is increased, and the third group of reflectors move upwards along the vertical direction to increase the optical path; the pump light power is increased, the thermal lens focal length is reduced, and the third group of reflectors move downwards along the vertical direction to reduce the optical path.
4. The laser amplifier of claim 1, further comprising a first set of dichroic mirrors; two dichroic mirrors in the first group of dichroic mirrors are arranged in the pumping light path in a splayed structure, the two dichroic mirrors are positioned on two sides of the second group of lenses, and the first group of dichroic mirrors are used for separating pumping light with shorter wavelength and laser with longer wavelength; the dichroic mirror far away from the pump light source is used for transmitting pump light and reflecting laser, and the dichroic mirror close to the pump light source is used for further reflecting the laser transmitted out of the dichroic mirror far away from the pump light source.
5. The laser amplifier of claim 1, further comprising a second set of dichroic mirrors and a third set of dichroic mirrors;
the second group of dichroic mirrors are arranged between the laser gain medium and the third group of lenses and are used for transmitting pump light and reflecting laser;
the third group of dichroic mirrors are arranged between the third group of lenses and the second group of reflectors and are used for transmitting the pump light and further reflecting the laser light which penetrates through the second group of dichroic mirrors;
the second group of dichroic mirrors comprise a first dichroic mirror and a second dichroic mirror, and the third group of dichroic mirrors comprise a third dichroic mirror and a fourth dichroic mirror; the first dichroic mirror and the third dichroic mirror are arranged in an inverted-V-shaped structure in the upper half part of the optical path of the pumping optical path in the vertical direction; the second dichroic mirror and the fourth dichroic mirror are arranged in a splayed structure in the lower half portion of the pumping optical path in the vertical direction.
6. The laser amplifier according to claim 5, wherein the laser light enters from the incident end lens, passes through the laser gain medium multiple times under the action of the third set of reflecting mirrors and the second set of dichroic mirrors, and finally exits from the exit end lens.
7. The laser amplifier of claim 5, wherein the laser gain medium equivalent thermal lens is confocal with the fourth lens group, and the optical path of the laser light from the end of the second amplification pass to the beginning of the third amplification pass of the laser gain medium is twice the focal length of the thermal lens.
8. The laser amplifier according to any one of claims 1 to 7, wherein the pumping light source comprises a plurality of point-like light source units;
the first group lens, the second group lens, and the third group lens each include lens units matching the number and positions of the light source units.
9. The laser amplifier of claim 8, wherein the lens elements in the same group of lenses are separate lenses or are located in the same lens array.
10. The laser amplifier according to any of claims 1-7, wherein the distance between the end face of the laser gain medium and the second group of lenses matches the focal length of the second group of lenses; the size of the pumping light spot on the laser gain medium is related to the focal length of the first group of lenses, the focal length of the second group of lenses and the diameter of the pumping light output optical fiber.
11. The laser amplifier according to any of claims 1-7, wherein the second set of mirrors are horizontal mirrors for turning the pump light back along a horizontal path.
12. The laser amplifier according to any of claims 1-7, wherein the laser gain medium comprises any of:
yb is YAG crystal, Nd is YVO4 crystal, Yb is KGW crystal, Yb is KYW crystal or Ti is sapphire crystal.
13. The laser amplifier according to any of claims 1-7, wherein the laser light passes 4 or more times through the laser gain medium.
14. The laser amplifier according to any of claims 1-7, wherein the first set of mirrors comprises: a reflective prism and/or a plane mirror.
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Cited By (1)
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| CN116299933A (en) * | 2023-05-18 | 2023-06-23 | 北京盛镭科技有限公司 | Optical adjustment frame, adjustment method, optical assembly and optical system |
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